diff --git a/packages/google_sign_in/google_sign_in_ios/CHANGELOG.md b/packages/google_sign_in/google_sign_in_ios/CHANGELOG.md
index 8081c058091c..5da10877ac7e 100644
--- a/packages/google_sign_in/google_sign_in_ios/CHANGELOG.md
+++ b/packages/google_sign_in/google_sign_in_ios/CHANGELOG.md
@@ -1,5 +1,6 @@
-## NEXT
+## 6.3.6
 
+* Converts the Pigeon host API from Objective-C to Swift.
 * Updates minimum supported SDK version to Flutter 3.41/Dart 3.11.
 
 ## 6.3.5
diff --git a/packages/google_sign_in/google_sign_in_ios/darwin/Tests/GoogleSignInTests.swift b/packages/google_sign_in/google_sign_in_ios/darwin/Tests/GoogleSignInTests.swift
index 9c7721b0313c..67fa950e8f37 100644
--- a/packages/google_sign_in/google_sign_in_ios/darwin/Tests/GoogleSignInTests.swift
+++ b/packages/google_sign_in/google_sign_in_ios/darwin/Tests/GoogleSignInTests.swift
@@ -7,11 +7,7 @@ import Testing
 
 @testable import google_sign_in_ios
 
-#if canImport(google_sign_in_ios_objc)
-  @testable import google_sign_in_ios_objc
-#endif
-
-#if os(OSX)
+#if os(macOS)
   import FlutterMacOS
 #else
   import Flutter
@@ -19,7 +15,7 @@ import Testing
 
 // Test implementation of ViewProvider.
 class TestViewProvider: ViewProvider {
-  #if os(OSX)
+  #if os(macOS)
     // The view containing the Flutter content.
     var view: NSView?
   #else
@@ -63,7 +59,7 @@ class TestSignIn: NSObject, GIDSignInProtocol {
   }
 
   func restorePreviousSignIn(completion: (((any GIDGoogleUserProtocol)?, Error?) -> Void)?) {
-    if let exception = exception {
+    if let exception {
       exception.raise()
     }
     if let user {
@@ -78,7 +74,7 @@ class TestSignIn: NSObject, GIDSignInProtocol {
   }
 
   func disconnect(completion: ((Error?) -> Void)?) {
-    if let exception = exception {
+    if let exception {
       exception.raise()
     }
     completion?(error)
@@ -92,7 +88,7 @@ class TestSignIn: NSObject, GIDSignInProtocol {
       nonce: String?,
       completion: ((GIDSignInResultProtocol?, Error?) -> Void)?
     ) {
-      if let exception = exception {
+      if let exception {
         exception.raise()
       }
       self.presentingViewController = presentingViewController
@@ -113,7 +109,7 @@ class TestSignIn: NSObject, GIDSignInProtocol {
       nonce: String?,
       completion: (((any GIDSignInResultProtocol)?, Error?) -> Void)?
     ) {
-      if let exception = exception {
+      if let exception {
         exception.raise()
       }
       self.presentingWindow = presentingWindow
@@ -130,10 +126,10 @@ class TestSignIn: NSObject, GIDSignInProtocol {
 }
 
 // Test implementation of GIDProfileDataProtocol.
-class TestProfileData: NSObject, GIDProfileDataProtocol {
+class TestProfileData: GIDProfileDataProtocol {
   var email: String
   var name: String
-  // A URL to return from imageURLWithDimension:.
+  // A URL to return from imageURL(withDimension:).
   var imageURL: URL?
 
   init(name: String, email: String, imageURL: URL?) {
@@ -152,7 +148,7 @@ class TestProfileData: NSObject, GIDProfileDataProtocol {
 }
 
 // Test implementation of GIDTokenProtocol.
-final class TestToken: NSObject, GIDTokenProtocol {
+final class TestToken: GIDTokenProtocol {
   let tokenString: String
   let expirationDate: Date?
 
@@ -163,7 +159,7 @@ final class TestToken: NSObject, GIDTokenProtocol {
 }
 
 // Test implementation of GIDSignInResultProtocol.
-class TestSignInResult: NSObject, GIDSignInResultProtocol {
+class TestSignInResult: GIDSignInResultProtocol {
   var user: any GIDGoogleUserProtocol
   var serverAuthCode: String?
 
@@ -174,7 +170,7 @@ class TestSignInResult: NSObject, GIDSignInResultProtocol {
 }
 
 // Test implementation of GIDGoogleUserProtocol.
-class TestGoogleUser: NSObject, GIDGoogleUserProtocol {
+class TestGoogleUser: GIDGoogleUserProtocol {
   var userID: String?
   var profile: (any GIDProfileDataProtocol)?
   var grantedScopes: [String]?
@@ -185,7 +181,7 @@ class TestGoogleUser: NSObject, GIDGoogleUserProtocol {
   // An exception to throw from methods.
   var exception: NSException?
 
-  // The result to return from addScopes:presentingViewController:completion:.
+  // The result to return from addScopes(_:presenting:completion:).
   var result: (any GIDSignInResultProtocol)?
 
   // The error to return from methods.
@@ -204,7 +200,7 @@ class TestGoogleUser: NSObject, GIDGoogleUserProtocol {
   }
 
   func refreshTokensIfNeeded(completion: @escaping ((any GIDGoogleUserProtocol)?, Error?) -> Void) {
-    if let exception = exception {
+    if let exception {
       exception.raise()
     }
     completion(self.error == nil ? self : nil, self.error)
@@ -218,12 +214,12 @@ class TestGoogleUser: NSObject, GIDGoogleUserProtocol {
     ) {
       self.requestedScopes = scopes
       self.presentingViewController = presentingViewController
-      if let exception = exception {
+      if let exception {
         exception.raise()
       }
       completion?(self.error == nil ? self.result : nil, self.error)
     }
-  #elseif os(OSX)
+  #elseif os(macOS)
     func addScopes(
       _ scopes: [String],
       presenting presentingWindow: NSWindow?,
@@ -231,7 +227,7 @@ class TestGoogleUser: NSObject, GIDGoogleUserProtocol {
     ) {
       self.requestedScopes = scopes
       self.presentingWindow = presentingWindow
-      if let exception = exception {
+      if let exception {
         exception.raise()
       }
       completion?(self.error == nil ? self.result : nil, self.error)
@@ -240,35 +236,36 @@ class TestGoogleUser: NSObject, GIDGoogleUserProtocol {
 }
 
 struct GoogleSignInPluginTests {
-  @Test func signOut() {
+  @Test func signOut() throws {
     let (plugin, fakeSignIn) = createTestPlugin()
-    var error: FlutterError?
-    plugin.signOutWithError(&error)
+    try plugin.signOut()
     #expect(fakeSignIn.signOutCalled == true)
-    #expect(error == nil)
   }
 
   @Test func disconnect() async {
     let (plugin, _) = createTestPlugin()
     await confirmation("expect result returns true") { confirmed in
-      plugin.disconnect { error in
-        #expect(error == nil)
+      plugin.disconnect { result in
+        switch result {
+        case .success:
+          break
+        case .failure(let error):
+          Issue.record("Unexpected error: \(error)")
+        }
         confirmed()
       }
     }
   }
 
   @Suite("configure") struct ConfigureTests {
-    @Test func configureFromAppInfoPlist() {
+    @Test func configureFromAppInfoPlist() throws {
       let (plugin, fakeSignIn) = createTestPlugin()
-      let params = FSIPlatformConfigurationParams.make(
-        withClientId: nil,
+      let params = PlatformConfigurationParams(
+        clientId: nil,
         serverClientId: nil,
         hostedDomain: "example.com")
 
-      var error: FlutterError?
-      plugin.configure(withParameters: params, error: &error)
-      #expect(error == nil)
+      try plugin.configure(params: params)
       // No configuration should be set, allowing the SDK to use its default behavior
       // (which is to load configuration information from the app's Info.plist).
       #expect(fakeSignIn.configuration == nil)
@@ -288,12 +285,12 @@ struct GoogleSignInPluginTests {
         dynamicServerClientId: String?,
         dynamicHostedDomain: String?,
         useGoogleServiceInfoPlist: Bool
-      )
+      ) throws
     {
       let (plugin, fakeSignIn) = createTestPlugin(
         googleServiceProperties: useGoogleServiceInfoPlist ? loadGoogleServiceInfo() : nil)
-      let params = FSIPlatformConfigurationParams.make(
-        withClientId: dynamicClientId,
+      let params = PlatformConfigurationParams(
+        clientId: dynamicClientId,
         serverClientId: dynamicServerClientId,
         hostedDomain: dynamicHostedDomain)
 
@@ -316,9 +313,7 @@ struct GoogleSignInPluginTests {
         expectedDomain = dynamicHostedDomain
       }
 
-      var error: FlutterError?
-      plugin.configure(withParameters: params, error: &error)
-      #expect(error == nil)
+      try plugin.configure(params: params)
       #expect(
         fakeSignIn.configuration?.clientID
           == expectedClientId)
@@ -342,16 +337,22 @@ struct GoogleSignInPluginTests {
       fakeSignIn.user = fakeUser
 
       await confirmation("completion called") { confirmed in
-        plugin.restorePreviousSignIn { result, error in
-          #expect(error == nil)
-          #expect(result?.error == nil)
-          #expect(result?.success != nil)
-          #expect(result?.success?.user.displayName == name)
-          #expect(result?.success?.user.email == email)
-          #expect(result?.success?.user.userId == userID)
-          #expect(result?.success?.user.photoUrl == imageURLString)
-          #expect(result?.success?.accessToken == accessToken)
-          #expect(result?.success?.serverAuthCode == nil)
+        plugin.restorePreviousSignIn { result in
+          switch result {
+          case .success(let signInResult):
+            guard let success = signInResult as? SignInSuccess else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(success.user.displayName == name)
+            #expect(success.user.email == email)
+            #expect(success.user.userId == userID)
+            #expect(success.user.photoUrl == imageURLString)
+            #expect(success.accessToken == accessToken)
+            #expect(success.serverAuthCode == nil)
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -365,10 +366,17 @@ struct GoogleSignInPluginTests {
       fakeSignIn.error = sdkError
 
       await confirmation("completion called") { confirmed in
-        plugin.restorePreviousSignIn { result, error in
-          #expect(error == nil)
-          #expect(result?.success == nil)
-          #expect(result?.error?.type == FSIGoogleSignInErrorCode.noAuthInKeychain)
+        plugin.restorePreviousSignIn { result in
+          switch result {
+          case .success(let signInResult):
+            guard let failure = signInResult as? SignInFailure else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(failure.type == GoogleSignInErrorCode.noAuthInKeychain)
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -381,23 +389,37 @@ struct GoogleSignInPluginTests {
       fakeSignIn.user = fakeUser
 
       await confirmation("completion called") { confirmed in
-        plugin.restorePreviousSignIn { result, error in
-          #expect(result == nil)
-          #expect(error?.code == "google_sign_in")
-          #expect(error?.message == "Google Sign-In succeeded without a user ID.")
+        plugin.restorePreviousSignIn { result in
+          switch result {
+          case .success(let signInResult):
+            Issue.record("Unexpected success: \(signInResult)")
+          case .failure(let error):
+            let pigeonError = error as! PigeonError
+            #expect(pigeonError.code == "google_sign_in")
+            #expect(pigeonError.message == "Google Sign-In succeeded without a user ID.")
+          }
           confirmed()
         }
       }
     }
 
-    @Test func restorePreviousSignInNeitherUserNorError() async {
+    @Test func restorePreviousSignInWithoutUserOrError() async {
       let (plugin, _) = createTestPlugin()
 
       await confirmation("completion called") { confirmed in
-        plugin.restorePreviousSignIn { result, error in
-          #expect(result == nil)
-          #expect(error?.code == "(null): 0")
-          #expect(error?.details as? String == "[Unsupported type: (null)]")
+        plugin.restorePreviousSignIn { result in
+          switch result {
+          case .success:
+            Issue.record("Expected a PigeonError when the SDK returns neither a user nor an error")
+          case .failure(let error):
+            guard let pigeonError = error as? PigeonError else {
+              Issue.record("Expected PigeonError, got \(error)")
+              break
+            }
+            #expect(pigeonError.code == "google_sign_in")
+            #expect(pigeonError.message == "Sign-in completed without a user or an error.")
+            #expect(pigeonError.details == nil)
+          }
           confirmed()
         }
       }
@@ -422,29 +444,34 @@ struct GoogleSignInPluginTests {
       fakeSignIn.signInResult = fakeSignInResult
 
       await confirmation("completion called") { confirmed in
-        plugin.signIn(withScopeHint: [], nonce: nil) { result, error in
-          #expect(error == nil)
-          #expect(result?.success?.user.displayName == "mockDisplay")
-          #expect(result?.success?.user.email == "mock@example.com")
-          #expect(result?.success?.user.userId == "mockID")
-          #expect(result?.success?.user.photoUrl == "https://example.com/profile.png")
-          #expect(result?.success?.accessToken == accessToken)
-          #expect(result?.success?.serverAuthCode == serverAuthCode)
+        plugin.signIn(scopeHint: [], nonce: nil) { result in
+          switch result {
+          case .success(let signInResult):
+            guard let success = signInResult as? SignInSuccess else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(success.user.displayName == "mockDisplay")
+            #expect(success.user.email == "mock@example.com")
+            #expect(success.user.userId == "mockID")
+            #expect(success.user.photoUrl == "https://example.com/profile.png")
+            #expect(success.accessToken == accessToken)
+            #expect(success.serverAuthCode == serverAuthCode)
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
     }
 
-    @Test func signInWithScopeHint() async {
+    @Test func signInWithScopeHint() async throws {
       let (plugin, fakeSignIn) = createTestPlugin()
-      var initializationError: FlutterError?
-      plugin.configure(
-        withParameters: FSIPlatformConfigurationParams.make(
-          withClientId: nil,
+      try plugin.configure(
+        params: PlatformConfigurationParams(
+          clientId: nil,
           serverClientId: nil,
-          hostedDomain: nil),
-        error: &initializationError)
-      #expect(initializationError == nil)
+          hostedDomain: nil))
 
       let fakeUser = TestGoogleUser("mockID")
       let fakeSignInResult = TestSignInResult(user: fakeUser)
@@ -453,10 +480,17 @@ struct GoogleSignInPluginTests {
       fakeSignIn.signInResult = fakeSignInResult
 
       await confirmation("completion called") { confirmed in
-        plugin.signIn(withScopeHint: requestedScopes, nonce: nil) { result, error in
-          #expect(error == nil)
-          #expect(result?.error == nil)
-          #expect(result?.success?.user.userId == "mockID")
+        plugin.signIn(scopeHint: requestedScopes, nonce: nil) { result in
+          switch result {
+          case .success(let signInResult):
+            guard let success = signInResult as? SignInSuccess else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(success.user.userId == "mockID")
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -464,16 +498,13 @@ struct GoogleSignInPluginTests {
       #expect(Set(fakeSignIn.additionalScopes ?? []) == Set(requestedScopes))
     }
 
-    @Test func signInWithNonce() async {
+    @Test func signInWithNonce() async throws {
       let (plugin, fakeSignIn) = createTestPlugin()
-      var initializationError: FlutterError?
-      plugin.configure(
-        withParameters: FSIPlatformConfigurationParams.make(
-          withClientId: nil,
+      try plugin.configure(
+        params: PlatformConfigurationParams(
+          clientId: nil,
           serverClientId: nil,
-          hostedDomain: nil),
-        error: &initializationError)
-      #expect(initializationError == nil)
+          hostedDomain: nil))
 
       let fakeUser = TestGoogleUser("mockID")
       let fakeSignInResult = TestSignInResult(user: fakeUser)
@@ -482,10 +513,17 @@ struct GoogleSignInPluginTests {
       fakeSignIn.signInResult = fakeSignInResult
 
       await confirmation("completion called") { confirmed in
-        plugin.signIn(withScopeHint: [], nonce: nonce) { result, error in
-          #expect(error == nil)
-          #expect(result?.error == nil)
-          #expect(result?.success?.user.userId == "mockID")
+        plugin.signIn(scopeHint: [], nonce: nonce) { result in
+          switch result {
+          case .success(let signInResult):
+            guard let success = signInResult as? SignInSuccess else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(success.user.userId == "mockID")
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -506,10 +544,17 @@ struct GoogleSignInPluginTests {
       fakeSignIn.error = sdkError
 
       await confirmation("completion called") { confirmed in
-        plugin.signIn(withScopeHint: [], nonce: nil) { result, error in
-          #expect(error == nil)
-          #expect(result?.error == nil)
-          #expect(result?.success?.user.userId == "mockID")
+        plugin.signIn(scopeHint: [], nonce: nil) { result in
+          switch result {
+          case .success(let signInResult):
+            guard let success = signInResult as? SignInSuccess else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(success.user.userId == "mockID")
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -522,12 +567,19 @@ struct GoogleSignInPluginTests {
       fakeSignIn.error = sdkError
 
       await confirmation("completion called") { confirmed in
-        plugin.signIn(withScopeHint: [], nonce: nil) { result, error in
-          // Known errors from the SDK are returned as structured data, not
-          // FlutterError.
-          #expect(error == nil)
-          #expect(result?.success == nil)
-          #expect(result?.error?.type == .canceled)
+        plugin.signIn(scopeHint: [], nonce: nil) { result in
+          switch result {
+          case .success(let signInResult):
+            // Known errors from the SDK are returned as structured data, not
+            // PigeonError.
+            guard let failure = signInResult as? SignInFailure else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(failure.type == .canceled)
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -541,13 +593,21 @@ struct GoogleSignInPluginTests {
         userInfo: nil)
 
       await confirmation("completion called") { confirmed in
-        plugin.signIn(withScopeHint: [], nonce: nil) { result, error in
-          // Unexpected errors, such as runtime exceptions, are returned as
-          // FlutterError.
-          #expect(result == nil)
-          #expect(error?.code == "google_sign_in")
-          #expect(error?.message == "MockReason")
-          #expect(error?.details as? String == "MockName")
+        plugin.signIn(scopeHint: [], nonce: nil) { result in
+          switch result {
+          case .success:
+            Issue.record("Expected a PigeonError for the runtime exception")
+          case .failure(let error):
+            // Unexpected errors, such as runtime exceptions, are returned as
+            // PigeonError.
+            guard let pigeonError = error as? PigeonError else {
+              Issue.record("Expected PigeonError, got \(error)")
+              break
+            }
+            #expect(pigeonError.code == "google_sign_in")
+            #expect(pigeonError.message == "MockReason")
+            #expect(pigeonError.details as? String == "MockName")
+          }
           confirmed()
         }
       }
@@ -564,11 +624,18 @@ struct GoogleSignInPluginTests {
       fakeUser.accessToken = TestToken("mockAccessToken")
 
       await confirmation("completion called") { confirmed in
-        plugin.refreshedAuthorizationTokens(forUser: fakeUser.userID!) { result, error in
-          #expect(error == nil)
-          #expect(result?.error == nil)
-          #expect(result?.success?.user.idToken == "mockIdToken")
-          #expect(result?.success?.accessToken == "mockAccessToken")
+        plugin.getRefreshedAuthorizationTokens(userId: fakeUser.userID!) { result in
+          switch result {
+          case .success(let signInResult):
+            guard let success = signInResult as? SignInSuccess else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(success.user.idToken == "mockIdToken")
+            #expect(success.accessToken == "mockAccessToken")
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -577,22 +644,29 @@ struct GoogleSignInPluginTests {
     @Test func refreshTokensUnkownUser() async {
       let (plugin, _) = createTestPlugin()
       await confirmation("completion called") { confirmed in
-        plugin.refreshedAuthorizationTokens(forUser: "unknownUser") { result, error in
-          #expect(error == nil)
-          #expect(result?.success == nil)
-          #expect(result?.error?.type == .userMismatch)
-          #expect(result?.error?.message == "The user is no longer signed in.")
+        plugin.getRefreshedAuthorizationTokens(userId: "unknownUser") { result in
+          switch result {
+          case .success(let signInResult):
+            guard let failure = signInResult as? SignInFailure else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(failure.type == .userMismatch)
+            #expect(failure.message == "The user is no longer signed in.")
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
     }
 
     @Test(arguments: [
-      (GIDSignInError.hasNoAuthInKeychain.rawValue, FSIGoogleSignInErrorCode.noAuthInKeychain),
-      (GIDSignInError.canceled.rawValue, .canceled),
+      (GIDSignInError.hasNoAuthInKeychain.rawValue, GoogleSignInErrorCode.noAuthInKeychain),
+      (GIDSignInError.canceled.rawValue, GoogleSignInErrorCode.canceled),
     ]) func refreshTokensGIDSignInErrorDomainErrors(
       signInSDKErrorCode: Int,
-      expectedPigeonErrorCode: FSIGoogleSignInErrorCode
+      expectedPigeonErrorCode: GoogleSignInErrorCode
     ) async {
       let (plugin, _) = createTestPlugin()
       let fakeUser = addSignedInUser(to: plugin)
@@ -603,10 +677,17 @@ struct GoogleSignInPluginTests {
       fakeUser.error = sdkError
 
       await confirmation("completion called") { confirmed in
-        plugin.refreshedAuthorizationTokens(forUser: fakeUser.userID!) { result, error in
-          #expect(error == nil)
-          #expect(result?.success == nil)
-          #expect(result?.error?.type == expectedPigeonErrorCode)
+        plugin.getRefreshedAuthorizationTokens(userId: fakeUser.userID!) { result in
+          switch result {
+          case .success(let signInResult):
+            guard let failure = signInResult as? SignInFailure else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(failure.type == expectedPigeonErrorCode)
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -626,11 +707,18 @@ struct GoogleSignInPluginTests {
       fakeUser.error = sdkError
 
       await confirmation("completion called") { confirmed in
-        plugin.refreshedAuthorizationTokens(forUser: fakeUser.userID!) { result, error in
-          #expect(result?.error == nil)
-          #expect(result?.success == nil)
-          let expectedCode = "\(errorDomain): \(errorCode)"
-          #expect(error?.code == expectedCode)
+        plugin.getRefreshedAuthorizationTokens(userId: fakeUser.userID!) { result in
+          switch result {
+          case .success:
+            Issue.record("Expected a PigeonError for a non-GID error domain")
+          case .failure(let error):
+            guard let pigeonError = error as? PigeonError else {
+              Issue.record("Expected PigeonError, got \(error)")
+              break
+            }
+            let expectedCode = "\(errorDomain): \(errorCode)"
+            #expect(pigeonError.code == expectedCode)
+          }
           confirmed()
         }
       }
@@ -649,9 +737,16 @@ struct GoogleSignInPluginTests {
       let scopes = ["mockScope1"]
 
       await confirmation("completion called") { confirmed in
-        plugin.addScopes(scopes, forUser: fakeUser.userID!) { result, error in
-          #expect(error == nil)
-          #expect(result?.success != nil)
+        plugin.addScopes(scopes, forUser: fakeUser.userID!) { result in
+          switch result {
+          case .success(let signInResult):
+            guard signInResult is SignInSuccess else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -661,21 +756,28 @@ struct GoogleSignInPluginTests {
     @Test func addScopesErrorsIfNotSignedIn() async {
       let (plugin, _) = createTestPlugin()
       await confirmation("completion called") { confirmed in
-        plugin.addScopes(["mockScope1"], forUser: "unknownUser") { result, error in
-          #expect(error == nil)
-          #expect(result?.success == nil)
-          #expect(result?.error?.type == .userMismatch)
+        plugin.addScopes(["mockScope1"], forUser: "unknownUser") { result in
+          switch result {
+          case .success(let signInResult):
+            guard let failure = signInResult as? SignInFailure else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(failure.type == .userMismatch)
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
     }
 
     @Test(arguments: [
-      (GIDSignInError.scopesAlreadyGranted.rawValue, FSIGoogleSignInErrorCode.scopesAlreadyGranted),
-      (GIDSignInError.mismatchWithCurrentUser.rawValue, FSIGoogleSignInErrorCode.userMismatch),
+      (GIDSignInError.scopesAlreadyGranted.rawValue, GoogleSignInErrorCode.scopesAlreadyGranted),
+      (GIDSignInError.mismatchWithCurrentUser.rawValue, GoogleSignInErrorCode.userMismatch),
     ]) func addScopesGIDSignInErrorDomainErrors(
       signInSDKErrorCode: Int,
-      expectedPigeonErrorCode: FSIGoogleSignInErrorCode
+      expectedPigeonErrorCode: GoogleSignInErrorCode
     ) async {
       let (plugin, _) = createTestPlugin()
       let fakeUser = addSignedInUser(to: plugin)
@@ -686,10 +788,17 @@ struct GoogleSignInPluginTests {
       fakeUser.error = sdkError
 
       await confirmation("completion called") { confirmed in
-        plugin.addScopes(["mockScope1"], forUser: fakeUser.userID!) { result, error in
-          #expect(error == nil)
-          #expect(result?.success == nil)
-          #expect(result?.error?.type == expectedPigeonErrorCode)
+        plugin.addScopes(["mockScope1"], forUser: fakeUser.userID!) { result in
+          switch result {
+          case .success(let signInResult):
+            guard let failure = signInResult as? SignInFailure else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(failure.type == expectedPigeonErrorCode)
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -703,9 +812,17 @@ struct GoogleSignInPluginTests {
       fakeUser.error = sdkError
 
       await confirmation("completion called") { confirmed in
-        plugin.addScopes(["mockScope1"], forUser: fakeUser.userID!) { result, error in
-          #expect(result == nil)
-          #expect(error?.code == "BogusDomain: 42")
+        plugin.addScopes(["mockScope1"], forUser: fakeUser.userID!) { result in
+          switch result {
+          case .success:
+            Issue.record("Expected a PigeonError for an unknown error domain")
+          case .failure(let error):
+            guard let pigeonError = error as? PigeonError else {
+              Issue.record("Expected PigeonError, got \(error)")
+              break
+            }
+            #expect(pigeonError.code == "BogusDomain: 42")
+          }
           confirmed()
         }
       }
@@ -721,11 +838,19 @@ struct GoogleSignInPluginTests {
         userInfo: nil)
 
       await confirmation("completion called") { confirmed in
-        plugin.addScopes([], forUser: fakeUser.userID!) { result, error in
-          #expect(result == nil)
-          #expect(error?.code == "request_scopes")
-          #expect(error?.message == "MockReason")
-          #expect(error?.details as? String == "MockName")
+        plugin.addScopes([], forUser: fakeUser.userID!) { result in
+          switch result {
+          case .success:
+            Issue.record("Expected a PigeonError for the runtime exception")
+          case .failure(let error):
+            guard let pigeonError = error as? PigeonError else {
+              Issue.record("Expected PigeonError, got \(error)")
+              break
+            }
+            #expect(pigeonError.code == "request_scopes")
+            #expect(pigeonError.message == "MockReason")
+            #expect(pigeonError.details as? String == "MockName")
+          }
           confirmed()
         }
       }
@@ -784,24 +909,31 @@ struct GoogleSignInPluginTests {
 
   @Suite("errorMapping") struct ErrorMappingTests {
     @Test(arguments: [
-      (GIDSignInError.keychain.rawValue, FSIGoogleSignInErrorCode.keychainError),
-      (GIDSignInError.EMM.rawValue, FSIGoogleSignInErrorCode.eemError),
-      (GIDSignInError.unknown.rawValue, FSIGoogleSignInErrorCode.unknown),
+      (GIDSignInError.keychain.rawValue, GoogleSignInErrorCode.keychainError),
+      (GIDSignInError.EMM.rawValue, GoogleSignInErrorCode.eemError),
+      (GIDSignInError.unknown.rawValue, GoogleSignInErrorCode.unknown),
       // Unrecognized SDK codes fall through to the default → unknown.
-      (12_345, FSIGoogleSignInErrorCode.unknown),
+      (12_345, GoogleSignInErrorCode.unknown),
     ]) func mapsRemainingGIDSignInErrorCodes(
       signInSDKErrorCode: Int,
-      expectedPigeonErrorCode: FSIGoogleSignInErrorCode
+      expectedPigeonErrorCode: GoogleSignInErrorCode
     ) async {
       let (plugin, fakeSignIn) = createTestPlugin()
       fakeSignIn.error = NSError(
         domain: kGIDSignInErrorDomain, code: signInSDKErrorCode, userInfo: nil)
 
       await confirmation("completion called") { confirmed in
-        plugin.signIn(withScopeHint: [], nonce: nil) { result, error in
-          #expect(error == nil)
-          #expect(result?.success == nil)
-          #expect(result?.error?.type == expectedPigeonErrorCode)
+        plugin.signIn(scopeHint: [], nonce: nil) { result in
+          switch result {
+          case .success(let signInResult):
+            guard let failure = signInResult as? SignInFailure else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(failure.type == expectedPigeonErrorCode)
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -823,20 +955,28 @@ struct GoogleSignInPluginTests {
       fakeUser.error = NSError(domain: "BogusDomain", code: 7, userInfo: userInfo)
 
       await confirmation("completion called") { confirmed in
-        plugin.refreshedAuthorizationTokens(forUser: fakeUser.userID!) { result, error in
-          #expect(result == nil)
-          #expect(error?.code == "BogusDomain: 7")
-          let details = error?.details as? [String: Any]
-          #expect(details?["string"] as? String == "ok")
-          #expect(details?["number"] as? NSNumber == NSNumber(value: 42))
-          #expect(details?["url"] as? String == "https://example.com/path")
-          #expect((details?["array"] as? [Any])?.count == 2)
-          #expect((details?["dict"] as? [String: Any])?["inner"] as? String == "value")
-          let nestedDetails = details?[NSUnderlyingErrorKey] as? [String: Any]
-          #expect(nestedDetails?["domain"] as? String == "NestedDomain")
-          #expect(nestedDetails?["code"] as? String == "99")
-          let unsupported = details?["unsupported"] as? String
-          #expect(unsupported?.contains("Unsupported type:") == true)
+        plugin.getRefreshedAuthorizationTokens(userId: fakeUser.userID!) { result in
+          switch result {
+          case .success:
+            Issue.record("Expected a PigeonError for a non-GID error domain")
+          case .failure(let error):
+            guard let pigeonError = error as? PigeonError else {
+              Issue.record("Expected PigeonError, got \(error)")
+              break
+            }
+            #expect(pigeonError.code == "BogusDomain: 7")
+            let details = pigeonError.details as? [String: any Sendable]
+            #expect(details?["string"] as? String == "ok")
+            #expect(details?["number"] as? NSNumber == NSNumber(value: 42))
+            #expect(details?["url"] as? String == "https://example.com/path")
+            #expect((details?["array"] as? [any Sendable])?.count == 2)
+            #expect((details?["dict"] as? [String: any Sendable])?["inner"] as? String == "value")
+            let nestedDetails = details?[NSUnderlyingErrorKey] as? [String: any Sendable]
+            #expect(nestedDetails?["domain"] as? String == "NestedDomain")
+            #expect(nestedDetails?["code"] as? String == "99")
+            let unsupported = details?["unsupported"] as? String
+            #expect(unsupported?.contains("Unsupported type:") == true)
+          }
           confirmed()
         }
       }
@@ -850,9 +990,18 @@ struct GoogleSignInPluginTests {
         domain: "DisconnectDomain", code: 3, userInfo: ["reason": "failed"])
 
       await confirmation("completion called") { confirmed in
-        plugin.disconnect { error in
-          #expect(error?.code == "DisconnectDomain: 3")
-          #expect((error?.details as? [String: Any])?["reason"] as? String == "failed")
+        plugin.disconnect { result in
+          switch result {
+          case .success:
+            Issue.record("Expected a PigeonError for a failed disconnect")
+          case .failure(let error):
+            guard let pigeonError = error as? PigeonError else {
+              Issue.record("Expected PigeonError, got \(error)")
+              break
+            }
+            #expect(pigeonError.code == "DisconnectDomain: 3")
+            #expect((pigeonError.details as? [String: Any])?["reason"] as? String == "failed")
+          }
           confirmed()
         }
       }
@@ -867,10 +1016,18 @@ struct GoogleSignInPluginTests {
       fakeSignIn.signInResult = TestSignInResult(user: fakeUser)
 
       await confirmation("completion called") { confirmed in
-        plugin.signIn(withScopeHint: [], nonce: nil) { result, error in
-          #expect(error == nil)
-          #expect(result?.success?.user.photoUrl == nil)
-          #expect(result?.success?.user.displayName == "Name")
+        plugin.signIn(scopeHint: [], nonce: nil) { result in
+          switch result {
+          case .success(let signInResult):
+            guard let success = signInResult as? SignInSuccess else {
+              Issue.record("Unexpected type for \(signInResult)")
+              break
+            }
+            #expect(success.user.photoUrl == nil)
+            #expect(success.user.displayName == "Name")
+          case .failure(let error):
+            Issue.record("Unexpected error: \(error)")
+          }
           confirmed()
         }
       }
@@ -899,10 +1056,18 @@ struct GoogleSignInPluginTests {
       let plugin = GoogleSignInPlugin(
         signIn: GIDSignInWrapper(), viewProvider: TestViewProvider())
       await confirmation("completion called") { confirmed in
-        plugin.signIn(withScopeHint: [], nonce: nil) { result, error in
-          #expect(result == nil)
-          #expect(error?.code == "google_sign_in: 0")
-          #expect(error?.message == "No host view available to present Google Sign-In.")
+        plugin.signIn(scopeHint: [], nonce: nil) { result in
+          switch result {
+          case .success:
+            Issue.record("Expected a PigeonError when no presenter is available")
+          case .failure(let error):
+            guard let pigeonError = error as? PigeonError else {
+              Issue.record("Expected PigeonError, got \(error)")
+              break
+            }
+            #expect(pigeonError.code == "google_sign_in: 0")
+            #expect(pigeonError.message == "No host view available to present Google Sign-In.")
+          }
           confirmed()
         }
       }
@@ -925,7 +1090,7 @@ struct GoogleSignInPluginTests {
         fakeSignIn.signInResult = TestSignInResult(user: TestGoogleUser("id"))
 
         await confirmation("completion called") { confirmed in
-          plugin.signIn(withScopeHint: [], nonce: nil) { _, _ in confirmed() }
+          plugin.signIn(scopeHint: [], nonce: nil) { _ in confirmed() }
         }
         #expect(fakeSignIn.presentingViewController === top)
       }
@@ -943,7 +1108,7 @@ struct GoogleSignInPluginTests {
         fakeSignIn.signInResult = TestSignInResult(user: TestGoogleUser("id"))
 
         await confirmation("completion called") { confirmed in
-          plugin.signIn(withScopeHint: [], nonce: nil) { _, _ in confirmed() }
+          plugin.signIn(scopeHint: [], nonce: nil) { _ in confirmed() }
         }
         #expect(fakeSignIn.presentingViewController === selected)
       }
@@ -958,7 +1123,7 @@ struct GoogleSignInPluginTests {
         fakeSignIn.signInResult = TestSignInResult(user: TestGoogleUser("id"))
 
         await confirmation("completion called") { confirmed in
-          plugin.signIn(withScopeHint: [], nonce: nil) { _, _ in confirmed() }
+          plugin.signIn(scopeHint: [], nonce: nil) { _ in confirmed() }
         }
         #expect(fakeSignIn.presentingViewController === presented)
       }
diff --git a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios.podspec b/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios.podspec
index 0664dd087f1f..fe7352b798ea 100644
--- a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios.podspec
+++ b/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios.podspec
@@ -12,8 +12,9 @@ Enables Google Sign-In in Flutter apps.
   s.license          = { :type => 'BSD', :file => '../LICENSE' }
   s.author           = { 'Flutter Team' => 'flutter-dev@googlegroups.com' }
   s.source           = { :http => 'https://github.com/flutter/packages/tree/main/packages/google_sign_in/google_sign_in_ios' }
-  # Combine google_sign_in_ios and google_sign_in_ios_objc sources into a single
-  # pod, unlike SwiftPM, where separate Swift and Objective-C targets are required.
+  # Remaining Objective-C is ExceptionCatcher (NSException can't be caught from
+  # Swift) plus a CocoaPods placeholder header. SwiftPM needs a separate Obj-C
+  # target; CocoaPods compiles both into one pod.
   s.source_files = 'google_sign_in_ios/Sources/google_sign_in_ios*/**/*.{h,m,swift}'
   s.public_header_files = 'google_sign_in_ios/Sources/google_sign_in_ios_objc/include/**/*.h'
   s.swift_version = '5.0'
diff --git a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Package.swift b/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Package.swift
index f3aa7ff0c04e..2c22d1072a9d 100644
--- a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Package.swift
+++ b/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Package.swift
@@ -31,13 +31,12 @@ let package = Package(
         .process("Resources")
       ]
     ),
+    // Swift cannot catch NSException, so ExceptionCatcher.m stays in a separate
+    // Objective-C target. That target also holds the CocoaPods placeholder
+    // header required to import google_sign_in_ios.h.
     .target(
       name: "google_sign_in_ios_objc",
-      publicHeadersPath: "include",
-      cSettings: [
-        .headerSearchPath("include/google_sign_in_ios"),
-        .headerSearchPath("include/google_sign_in_ios_objc"),
-      ]
+      publicHeadersPath: "include/google_sign_in_ios_objc"
     ),
   ]
 )
diff --git a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios/GoogleSignInPlugin.swift b/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios/GoogleSignInPlugin.swift
index eaa5bdb069da..11c64a864f07 100644
--- a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios/GoogleSignInPlugin.swift
+++ b/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios/GoogleSignInPlugin.swift
@@ -31,17 +31,17 @@ private func loadGoogleServiceInfo() -> [String: Any]? {
   return NSDictionary(contentsOfFile: plistPath) as? [String: Any]
 }
 
-/// Deep-converts values to something that can be safely encoded with the standard message codec,
-/// for use in making NSError userInfo values safe to send as FlutterError details.
-private func sanitizedUserInfo(_ value: Any?) -> Any {
+/// Deep-converts a value to something that can be encoded with the standard
+/// message codec, for use as Pigeon error details.
+private func sanitizedCodecValue(_ value: Any) -> any Sendable {
   switch value {
   case let error as NSError:
     return [
       "domain": error.domain,
       "code": "\(error.code)",
       "localizedDescription": error.localizedDescription,
-      "userInfo": sanitizedUserInfo(error.userInfo),
-    ]
+      "userInfo": sanitizedCodecDictionary(error.userInfo),
+    ] as [String: any Sendable]
   case let string as String:
     return string
   case let url as URL:
@@ -49,35 +49,39 @@ private func sanitizedUserInfo(_ value: Any?) -> Any {
   case let number as NSNumber:
     return number
   case let array as [Any]:
-    return array.map { sanitizedUserInfo($0) }
+    return array.map { sanitizedCodecValue($0) }
   case let dict as [AnyHashable: Any]:
-    var safeValues: [AnyHashable: Any] = [:]
-    safeValues.reserveCapacity(dict.count)
-    for (key, nestedValue) in dict {
-      safeValues[key] = sanitizedUserInfo(nestedValue)
-    }
-    return safeValues
+    return sanitizedCodecDictionary(dict)
   default:
-    guard let value else {
-      return "[Unsupported type: (null)]"
-    }
     return "[Unsupported type: \(String(describing: type(of: value)))]"
   }
 }
 
-/// Maps an NSError to a corresponding FlutterError.
-///
-/// This should only be used when an error can't be recognized and mapped to a
-/// GoogleSignInErrorCode.
-private func flutterError(from error: NSError?) -> FlutterError {
-  return FlutterError(
-    code: String(format: "%@: %ld", error?.domain ?? "(null)", error?.code ?? 0),
-    message: error?.localizedDescription,
-    details: sanitizedUserInfo(error?.userInfo))
+private func sanitizedCodecDictionary(_ dict: [AnyHashable: Any]) -> [String: any Sendable] {
+  var safeValues: [String: any Sendable] = [:]
+  safeValues.reserveCapacity(dict.count)
+  for (key, nestedValue) in dict {
+    let stringKey = key as? String ?? String(describing: key)
+    safeValues[stringKey] = sanitizedCodecValue(nestedValue)
+  }
+  return safeValues
+}
+
+extension PigeonError {
+  /// Maps an NSError to a corresponding PigeonError.
+  ///
+  /// This should only be used when an error can't be recognized and mapped to a
+  /// GoogleSignInErrorCode.
+  static func make(from error: NSError) -> PigeonError {
+    return PigeonError(
+      code: "\(error.domain): \(error.code)",
+      message: error.localizedDescription,
+      details: sanitizedCodecDictionary(error.userInfo))
+  }
 }
 
 /// Maps a GIDSignInErrorCode to the corresponding Pigeon GoogleSignInErrorCode.
-private func pigeonErrorCode(for gidSignInErrorCode: Int) -> FSIGoogleSignInErrorCode {
+private func pigeonErrorCode(for gidSignInErrorCode: Int) -> GoogleSignInErrorCode {
   switch gidSignInErrorCode {
   case GIDSignInError.keychain.rawValue:
     return .keychainError
@@ -96,7 +100,7 @@ private func pigeonErrorCode(for gidSignInErrorCode: Int) -> FSIGoogleSignInErro
   }
 }
 
-public final class GoogleSignInPlugin: NSObject, FlutterPlugin, FSIGoogleSignInApi {
+public final class GoogleSignInPlugin: NSObject, FlutterPlugin, GoogleSignInApi {
   /// Instance used to manage Google Sign In authentication including
   /// sign in, sign out, and requesting additional scopes.
   let signIn: any GIDSignInProtocol
@@ -120,7 +124,7 @@ public final class GoogleSignInPlugin: NSObject, FlutterPlugin, FSIGoogleSignInA
     #else
       let messenger = registrar.messenger
     #endif
-    SetUpFSIGoogleSignInApi(messenger, instance)
+    GoogleSignInApiSetup.setUp(binaryMessenger: messenger, api: instance)
   }
 
   /// Inject view provider for testing.
@@ -177,12 +181,9 @@ public final class GoogleSignInPlugin: NSObject, FlutterPlugin, FSIGoogleSignInA
     return handled
   }
 
-  // MARK: - FSIGoogleSignInApi
+  // MARK: - GoogleSignInApi
 
-  public func configure(
-    withParameters params: FSIPlatformConfigurationParams,
-    error: AutoreleasingUnsafeMutablePointer<FlutterError?>
-  ) {
+  func configure(params: PlatformConfigurationParams) throws {
     // If configuration information was passed from Dart, or present in GoogleService-Info.plist,
     // use that. Otherwise, keep the default configuration, which GIDSignIn will automatically
     // populate from Info.plist values (the recommended configuration method).
@@ -195,19 +196,17 @@ public final class GoogleSignInPlugin: NSObject, FlutterPlugin, FSIGoogleSignInA
     }
   }
 
-  public func restorePreviousSignIn(
-    completion: @escaping (FSISignInResult?, FlutterError?) -> Void
-  ) {
+  func restorePreviousSignIn(completion: @escaping (Result<SignInResult, Error>) -> Void) {
     signIn.restorePreviousSignIn { [weak self] user, error in
       self?.handleAuthResult(
         user: user, serverAuthCode: nil, error: error, completion: completion)
     }
   }
 
-  public func signIn(
-    withScopeHint scopeHint: [String],
+  func signIn(
+    scopeHint: [String],
     nonce: String?,
-    completion: @escaping (FSISignInResult?, FlutterError?) -> Void
+    completion: @escaping (Result<SignInResult, Error>) -> Void
   ) {
     let exception = performSignIn(hint: nil, additionalScopes: scopeHint, nonce: nonce) {
       [weak self] signInResult, error in
@@ -219,25 +218,23 @@ public final class GoogleSignInPlugin: NSObject, FlutterPlugin, FSIGoogleSignInA
     }
     if let exception {
       completion(
-        nil,
-        FlutterError(
-          code: "google_sign_in", message: exception.reason, details: exception.name.rawValue))
+        .failure(
+          PigeonError(
+            code: "google_sign_in", message: exception.reason, details: exception.name.rawValue)))
     }
   }
 
-  public func refreshedAuthorizationTokens(
-    forUser userId: String,
-    completion: @escaping (FSISignInResult?, FlutterError?) -> Void
+  func getRefreshedAuthorizationTokens(
+    userId: String,
+    completion: @escaping (Result<SignInResult, Error>) -> Void
   ) {
     guard let user = usersByIdentifier[userId] else {
       completion(
-        FSISignInResult.make(
-          with: nil,
-          error: FSISignInFailure.make(
-            withType: .userMismatch,
+        .success(
+          SignInFailure(
+            type: .userMismatch,
             message: "The user is no longer signed in.",
-            details: nil)),
-        nil)
+            details: nil)))
       return
     }
 
@@ -247,20 +244,18 @@ public final class GoogleSignInPlugin: NSObject, FlutterPlugin, FSIGoogleSignInA
     }
   }
 
-  public func addScopes(
+  func addScopes(
     _ scopes: [String],
     forUser userId: String,
-    completion: @escaping (FSISignInResult?, FlutterError?) -> Void
+    completion: @escaping (Result<SignInResult, Error>) -> Void
   ) {
     guard let user = usersByIdentifier[userId] else {
       completion(
-        FSISignInResult.make(
-          with: nil,
-          error: FSISignInFailure.make(
-            withType: .userMismatch,
+        .success(
+          SignInFailure(
+            type: .userMismatch,
             message: "The user is no longer signed in.",
-            details: nil)),
-        nil)
+            details: nil)))
       return
     }
 
@@ -273,25 +268,25 @@ public final class GoogleSignInPlugin: NSObject, FlutterPlugin, FSIGoogleSignInA
     }
     if let exception {
       completion(
-        nil,
-        FlutterError(
-          code: "request_scopes", message: exception.reason, details: exception.name.rawValue))
+        .failure(
+          PigeonError(
+            code: "request_scopes", message: exception.reason, details: exception.name.rawValue)))
     }
   }
 
-  public func signOutWithError(_ error: AutoreleasingUnsafeMutablePointer<FlutterError?>) {
+  func signOut() throws {
     signIn.signOut()
     // usersByIdentifier is left populated, because the SDK may still support some operations on the
     // GIDGoogleUser object (e.g., returning existing, non-expired tokens). Operations that the SDK
     // doesn't support will return SDK errors that we can handle as normal.
   }
 
-  public func disconnect(completion: @escaping (FlutterError?) -> Void) {
+  func disconnect(completion: @escaping (Result<Void, Error>) -> Void) {
     signIn.disconnect { error in
       if let error {
-        completion(flutterError(from: error as NSError))
+        completion(.failure(PigeonError.make(from: error as NSError)))
       } else {
-        completion(nil)
+        completion(.success(()))
       }
     }
   }
@@ -372,7 +367,7 @@ public final class GoogleSignInPlugin: NSObject, FlutterPlugin, FSIGoogleSignInA
     user: (any GIDGoogleUserProtocol)?,
     serverAuthCode: String?,
     error: Error?,
-    completion: @escaping (FSISignInResult?, FlutterError?) -> Void
+    completion: @escaping (Result<SignInResult, Error>) -> Void
   ) {
     if let user {
       didSignIn(for: user, serverAuthCode: serverAuthCode, completion: completion)
@@ -384,30 +379,37 @@ public final class GoogleSignInPlugin: NSObject, FlutterPlugin, FSIGoogleSignInA
     let nsError = error as NSError?
     if let nsError, nsError.domain == kGIDSignInErrorDomain {
       completion(
-        FSISignInResult.make(
-          with: nil,
-          error: FSISignInFailure.make(
-            withType: pigeonErrorCode(for: nsError.code),
+        .success(
+          SignInFailure(
+            type: pigeonErrorCode(for: nsError.code),
             message: nsError.localizedDescription,
-            details: sanitizedUserInfo(nsError.userInfo))),
-        nil)
+            details: sanitizedCodecDictionary(nsError.userInfo))))
+    } else if let nsError {
+      completion(.failure(PigeonError.make(from: nsError)))
     } else {
-      completion(nil, flutterError(from: nsError))
+      // GIDSignIn is expected to provide a user or an error. Keep a defensive
+      // fallback with a clear message rather than reporting a codec placeholder.
+      completion(
+        .failure(
+          PigeonError(
+            code: "google_sign_in",
+            message: "Sign-in completed without a user or an error.",
+            details: nil)))
     }
   }
 
   private func didSignIn(
     for user: any GIDGoogleUserProtocol,
     serverAuthCode: String?,
-    completion: @escaping (FSISignInResult?, FlutterError?) -> Void
+    completion: @escaping (Result<SignInResult, Error>) -> Void
   ) {
     guard let userID = user.userID else {
       completion(
-        nil,
-        FlutterError(
-          code: "google_sign_in",
-          message: "Google Sign-In succeeded without a user ID.",
-          details: nil))
+        .failure(
+          PigeonError(
+            code: "google_sign_in",
+            message: "Google Sign-In succeeded without a user ID.",
+            details: nil)))
       return
     }
     usersByIdentifier[userID] = user
@@ -418,20 +420,19 @@ public final class GoogleSignInPlugin: NSObject, FlutterPlugin, FSIGoogleSignInA
       photoURL = user.profile?.imageURL(withDimension: 1337)
     }
 
-    let userData = FSIUserData.make(
-      withDisplayName: user.profile?.name,
+    let userData = UserData(
+      displayName: user.profile?.name,
       email: user.profile?.email ?? "",
       userId: userID,
       photoUrl: photoURL?.absoluteString,
       idToken: user.idToken?.tokenString)
-    let result = FSISignInResult.make(
-      with: FSISignInSuccess.make(
-        withUser: userData,
-        accessToken: user.accessToken.tokenString,
-        grantedScopes: user.grantedScopes ?? [],
-        serverAuthCode: serverAuthCode),
-      error: nil)
-    completion(result, nil)
+    completion(
+      .success(
+        SignInSuccess(
+          user: userData,
+          accessToken: user.accessToken.tokenString,
+          grantedScopes: user.grantedScopes ?? [],
+          serverAuthCode: serverAuthCode)))
   }
 
   #if os(iOS)
diff --git a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios/messages.g.swift b/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios/messages.g.swift
new file mode 100644
index 000000000000..5e01d19c4ad4
--- /dev/null
+++ b/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios/messages.g.swift
@@ -0,0 +1,673 @@
+// Copyright 2013 The Flutter Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+// Autogenerated from Pigeon (v27.3.2), do not edit directly.
+// See also: https://pub.dev/packages/pigeon
+
+import Foundation
+
+#if os(iOS)
+  import Flutter
+#elseif os(macOS)
+  import FlutterMacOS
+#else
+  #error("Unsupported platform.")
+#endif
+
+/// Error class for passing custom error details to Dart side.
+final class PigeonError: Error {
+  let code: String
+  let message: String?
+  let details: Sendable?
+
+  init(code: String, message: String?, details: Sendable?) {
+    self.code = code
+    self.message = message
+    self.details = details
+  }
+
+  var localizedDescription: String {
+    return
+      "PigeonError(code: \(code), message: \(message ?? "<nil>"), details: \(details ?? "<nil>")"
+  }
+}
+
+private func wrapResult(_ result: Any?) -> [Any?] {
+  return [result]
+}
+
+private func wrapError(_ error: Any) -> [Any?] {
+  if let pigeonError = error as? PigeonError {
+    return [
+      pigeonError.code,
+      pigeonError.message,
+      pigeonError.details,
+    ]
+  }
+  if let flutterError = error as? FlutterError {
+    return [
+      flutterError.code,
+      flutterError.message,
+      flutterError.details,
+    ]
+  }
+  return [
+    "\(error)",
+    "\(Swift.type(of: error))",
+    "Stacktrace: \(Thread.callStackSymbols)",
+  ]
+}
+
+enum MessagesPigeonInternal {
+  static func isNullish(_ value: Any?) -> Bool {
+    guard let innerValue = value else {
+      return true
+    }
+
+    if case Optional<Any>.some(Optional<Any>.none) = value {
+      return true
+    }
+
+    return innerValue is NSNull
+  }
+  static func doubleEquals(_ lhs: Double, _ rhs: Double) -> Bool {
+    return (lhs.isNaN && rhs.isNaN) || lhs == rhs
+  }
+
+  static func doubleHash(_ value: Double, _ hasher: inout Hasher) {
+    if value.isNaN {
+      hasher.combine(0x7FF8_0000_0000_0000)
+    } else {
+      // Normalize -0.0 to 0.0
+      hasher.combine(value == 0 ? 0 : value)
+    }
+  }
+
+  static func deepEquals(_ lhs: Any?, _ rhs: Any?) -> Bool {
+    let cleanLhs = nilOrValue(lhs) as Any?
+    let cleanRhs = nilOrValue(rhs) as Any?
+    switch (cleanLhs, cleanRhs) {
+    case (nil, nil):
+      return true
+
+    case (nil, _), (_, nil):
+      return false
+
+    case (let lhs as AnyObject, let rhs as AnyObject) where lhs === rhs:
+      return true
+
+    case is (Void, Void):
+      return true
+
+    case (let lhsArray, let rhsArray) as ([Any?], [Any?]):
+      guard lhsArray.count == rhsArray.count else { return false }
+      for (index, element) in lhsArray.enumerated() {
+        if !deepEquals(element, rhsArray[index]) {
+          return false
+        }
+      }
+      return true
+
+    case (let lhsArray, let rhsArray) as ([Double], [Double]):
+      guard lhsArray.count == rhsArray.count else { return false }
+      for (index, element) in lhsArray.enumerated() {
+        if !doubleEquals(element, rhsArray[index]) {
+          return false
+        }
+      }
+      return true
+
+    case (let lhsDictionary, let rhsDictionary) as ([AnyHashable: Any?], [AnyHashable: Any?]):
+      guard lhsDictionary.count == rhsDictionary.count else { return false }
+      for (lhsKey, lhsValue) in lhsDictionary {
+        var found = false
+        for (rhsKey, rhsValue) in rhsDictionary {
+          if deepEquals(lhsKey, rhsKey) {
+            if deepEquals(lhsValue, rhsValue) {
+              found = true
+              break
+            } else {
+              return false
+            }
+          }
+        }
+        if !found { return false }
+      }
+      return true
+
+    case (let lhs as Double, let rhs as Double):
+      return doubleEquals(lhs, rhs)
+
+    case (let lhsHashable, let rhsHashable) as (AnyHashable, AnyHashable):
+      return lhsHashable == rhsHashable
+
+    default:
+      return false
+    }
+  }
+
+  static func deepHash(value: Any?, hasher: inout Hasher) {
+    let cleanValue = nilOrValue(value) as Any?
+    if let cleanValue = cleanValue {
+      if let doubleValue = cleanValue as? Double {
+        doubleHash(doubleValue, &hasher)
+      } else if let valueList = cleanValue as? [Any?] {
+        for item in valueList {
+          deepHash(value: item, hasher: &hasher)
+        }
+      } else if let valueList = cleanValue as? [Double] {
+        for item in valueList {
+          doubleHash(item, &hasher)
+        }
+      } else if let valueDict = cleanValue as? [AnyHashable: Any?] {
+        var result = 0
+        for (key, value) in valueDict {
+          var entryKeyHasher = Hasher()
+          deepHash(value: key, hasher: &entryKeyHasher)
+          var entryValueHasher = Hasher()
+          deepHash(value: value, hasher: &entryValueHasher)
+          result = result &+ ((entryKeyHasher.finalize() &* 31) ^ entryValueHasher.finalize())
+        }
+        hasher.combine(result)
+      } else if let hashableValue = cleanValue as? AnyHashable {
+        hasher.combine(hashableValue)
+      } else {
+        hasher.combine(String(describing: cleanValue))
+      }
+    } else {
+      hasher.combine(0)
+    }
+  }
+
+}
+
+private func nilOrValue<T>(_ value: Any?) -> T? {
+  if value is NSNull { return nil }
+  return value as! T?
+}
+
+/// Enum mapping of known codes from
+/// https://developers.google.com/identity/sign-in/ios/reference/Enums/GIDSignInErrorCode
+enum GoogleSignInErrorCode: Int, CaseIterable {
+  /// Either the underlying kGIDSignInErrorCodeUnknown, or a code that isn't
+  /// a known code mapped to a value below.
+  case unknown = 0
+  /// kGIDSignInErrorCodeKeychain; an error reading or writing to keychain.
+  case keychainError = 1
+  /// kGIDSignInErrorCodeHasNoAuthInKeychain; no auth present in the keychain.
+  ///
+  /// For restorePreviousSignIn, this indicates that there is no sign in to
+  /// restore.
+  case noAuthInKeychain = 2
+  /// kGIDSignInErrorCodeCanceled; the request was canceled by the user.
+  case canceled = 3
+  /// kGIDSignInErrorCodeEMM; an enterprise management error occurred.
+  case eemError = 4
+  /// kGIDSignInErrorCodeScopesAlreadyGranted; the requested scopes have already
+  /// been granted.
+  case scopesAlreadyGranted = 5
+  /// kGIDSignInErrorCodeMismatchWithCurrentUser; an operation was requested on
+  /// a non-current user.
+  case userMismatch = 6
+}
+
+/// Generated class from Pigeon that represents data sent in messages.
+struct PlatformConfigurationParams: Hashable, CustomStringConvertible {
+  var clientId: String? = nil
+  var serverClientId: String? = nil
+  var hostedDomain: String? = nil
+
+  // swift-format-ignore: AlwaysUseLowerCamelCase
+  static func fromList(_ pigeonVar_list: [Any?]) -> PlatformConfigurationParams? {
+    let clientId: String? = nilOrValue(pigeonVar_list[0])
+    let serverClientId: String? = nilOrValue(pigeonVar_list[1])
+    let hostedDomain: String? = nilOrValue(pigeonVar_list[2])
+
+    return PlatformConfigurationParams(
+      clientId: clientId,
+      serverClientId: serverClientId,
+      hostedDomain: hostedDomain
+    )
+  }
+  func toList() -> [Any?] {
+    return [
+      clientId,
+      serverClientId,
+      hostedDomain,
+    ]
+  }
+  static func == (lhs: PlatformConfigurationParams, rhs: PlatformConfigurationParams) -> Bool {
+    if Swift.type(of: lhs) != Swift.type(of: rhs) {
+      return false
+    }
+    return MessagesPigeonInternal.deepEquals(lhs.clientId, rhs.clientId)
+      && MessagesPigeonInternal.deepEquals(lhs.serverClientId, rhs.serverClientId)
+      && MessagesPigeonInternal.deepEquals(lhs.hostedDomain, rhs.hostedDomain)
+  }
+
+  func hash(into hasher: inout Hasher) {
+    hasher.combine("PlatformConfigurationParams")
+    MessagesPigeonInternal.deepHash(value: clientId, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: serverClientId, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: hostedDomain, hasher: &hasher)
+  }
+
+  public var description: String {
+    return
+      "PlatformConfigurationParams(clientId: \(String(describing: clientId)), serverClientId: \(String(describing: serverClientId)), hostedDomain: \(String(describing: hostedDomain)))"
+  }
+}
+
+/// Pigeon version of GoogleSignInUserData + AuthenticationTokenData.
+///
+/// See GoogleSignInUserData and AuthenticationTokenData for details.
+///
+/// Generated class from Pigeon that represents data sent in messages.
+struct UserData: Hashable, CustomStringConvertible {
+  var displayName: String? = nil
+  var email: String
+  var userId: String
+  var photoUrl: String? = nil
+  var idToken: String? = nil
+
+  // swift-format-ignore: AlwaysUseLowerCamelCase
+  static func fromList(_ pigeonVar_list: [Any?]) -> UserData? {
+    let displayName: String? = nilOrValue(pigeonVar_list[0])
+    let email = pigeonVar_list[1] as! String
+    let userId = pigeonVar_list[2] as! String
+    let photoUrl: String? = nilOrValue(pigeonVar_list[3])
+    let idToken: String? = nilOrValue(pigeonVar_list[4])
+
+    return UserData(
+      displayName: displayName,
+      email: email,
+      userId: userId,
+      photoUrl: photoUrl,
+      idToken: idToken
+    )
+  }
+  func toList() -> [Any?] {
+    return [
+      displayName,
+      email,
+      userId,
+      photoUrl,
+      idToken,
+    ]
+  }
+  static func == (lhs: UserData, rhs: UserData) -> Bool {
+    if Swift.type(of: lhs) != Swift.type(of: rhs) {
+      return false
+    }
+    return MessagesPigeonInternal.deepEquals(lhs.displayName, rhs.displayName)
+      && MessagesPigeonInternal.deepEquals(lhs.email, rhs.email)
+      && MessagesPigeonInternal.deepEquals(lhs.userId, rhs.userId)
+      && MessagesPigeonInternal.deepEquals(lhs.photoUrl, rhs.photoUrl)
+      && MessagesPigeonInternal.deepEquals(lhs.idToken, rhs.idToken)
+  }
+
+  func hash(into hasher: inout Hasher) {
+    hasher.combine("UserData")
+    MessagesPigeonInternal.deepHash(value: displayName, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: email, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: userId, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: photoUrl, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: idToken, hasher: &hasher)
+  }
+
+  public var description: String {
+    return
+      "UserData(displayName: \(String(describing: displayName)), email: \(String(describing: email)), userId: \(String(describing: userId)), photoUrl: \(String(describing: photoUrl)), idToken: \(String(describing: idToken)))"
+  }
+}
+
+/// The response from an auth call.
+///
+/// Generated class from Pigeon that represents data sent in messages.
+/// This protocol should not be extended by any user class outside of the generated file.
+protocol SignInResult {
+
+}
+
+/// A sign in failure.
+///
+/// Generated class from Pigeon that represents data sent in messages.
+struct SignInFailure: SignInResult {
+  /// The type of failure.
+  var type: GoogleSignInErrorCode
+  /// The message associated with the failure, if any.
+  var message: String? = nil
+  /// Extra details about the failure, if any.
+  var details: Any? = nil
+
+  // swift-format-ignore: AlwaysUseLowerCamelCase
+  static func fromList(_ pigeonVar_list: [Any?]) -> SignInFailure? {
+    let type = pigeonVar_list[0] as! GoogleSignInErrorCode
+    let message: String? = nilOrValue(pigeonVar_list[1])
+    let details: Any? = pigeonVar_list[2]
+
+    return SignInFailure(
+      type: type,
+      message: message,
+      details: details
+    )
+  }
+  func toList() -> [Any?] {
+    return [
+      type,
+      message,
+      details,
+    ]
+  }
+  static func == (lhs: SignInFailure, rhs: SignInFailure) -> Bool {
+    if Swift.type(of: lhs) != Swift.type(of: rhs) {
+      return false
+    }
+    return MessagesPigeonInternal.deepEquals(lhs.type, rhs.type)
+      && MessagesPigeonInternal.deepEquals(lhs.message, rhs.message)
+      && MessagesPigeonInternal.deepEquals(lhs.details, rhs.details)
+  }
+
+  func hash(into hasher: inout Hasher) {
+    hasher.combine("SignInFailure")
+    MessagesPigeonInternal.deepHash(value: type, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: message, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: details, hasher: &hasher)
+  }
+
+  public var description: String {
+    return
+      "SignInFailure(type: \(String(describing: type)), message: \(String(describing: message)), details: \(String(describing: details)))"
+  }
+}
+
+/// A successful auth result.
+///
+/// Corresponds to the information in a native GIDSignInResult. Because of the
+/// structure of the Google Sign In SDK, this has information corresponding to
+/// both authn and authz steps, even though incremental authorization is
+/// supported.
+///
+/// Generated class from Pigeon that represents data sent in messages.
+struct SignInSuccess: SignInResult {
+  var user: UserData
+  var accessToken: String
+  var grantedScopes: [String]
+  var serverAuthCode: String? = nil
+
+  // swift-format-ignore: AlwaysUseLowerCamelCase
+  static func fromList(_ pigeonVar_list: [Any?]) -> SignInSuccess? {
+    let user = pigeonVar_list[0] as! UserData
+    let accessToken = pigeonVar_list[1] as! String
+    let grantedScopes = pigeonVar_list[2] as! [String]
+    let serverAuthCode: String? = nilOrValue(pigeonVar_list[3])
+
+    return SignInSuccess(
+      user: user,
+      accessToken: accessToken,
+      grantedScopes: grantedScopes,
+      serverAuthCode: serverAuthCode
+    )
+  }
+  func toList() -> [Any?] {
+    return [
+      user,
+      accessToken,
+      grantedScopes,
+      serverAuthCode,
+    ]
+  }
+  static func == (lhs: SignInSuccess, rhs: SignInSuccess) -> Bool {
+    if Swift.type(of: lhs) != Swift.type(of: rhs) {
+      return false
+    }
+    return MessagesPigeonInternal.deepEquals(lhs.user, rhs.user)
+      && MessagesPigeonInternal.deepEquals(lhs.accessToken, rhs.accessToken)
+      && MessagesPigeonInternal.deepEquals(lhs.grantedScopes, rhs.grantedScopes)
+      && MessagesPigeonInternal.deepEquals(lhs.serverAuthCode, rhs.serverAuthCode)
+  }
+
+  func hash(into hasher: inout Hasher) {
+    hasher.combine("SignInSuccess")
+    MessagesPigeonInternal.deepHash(value: user, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: accessToken, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: grantedScopes, hasher: &hasher)
+    MessagesPigeonInternal.deepHash(value: serverAuthCode, hasher: &hasher)
+  }
+
+  public var description: String {
+    return
+      "SignInSuccess(user: \(String(describing: user)), accessToken: \(String(describing: accessToken)), grantedScopes: \(String(describing: grantedScopes)), serverAuthCode: \(String(describing: serverAuthCode)))"
+  }
+}
+
+private class MessagesPigeonCodecReader: FlutterStandardReader {
+  override func readValue(ofType type: UInt8) -> Any? {
+    switch type {
+    case 129:
+      let enumResultAsInt: Int? = nilOrValue(self.readValue() as! Int?)
+      if let enumResultAsInt = enumResultAsInt {
+        return GoogleSignInErrorCode(rawValue: enumResultAsInt)
+      }
+      return nil
+    case 130:
+      return PlatformConfigurationParams.fromList(self.readValue() as! [Any?])
+    case 131:
+      return UserData.fromList(self.readValue() as! [Any?])
+    case 132:
+      return SignInFailure.fromList(self.readValue() as! [Any?])
+    case 133:
+      return SignInSuccess.fromList(self.readValue() as! [Any?])
+    default:
+      return super.readValue(ofType: type)
+    }
+  }
+}
+
+private class MessagesPigeonCodecWriter: FlutterStandardWriter {
+  override func writeValue(_ value: Any) {
+    if let value = value as? GoogleSignInErrorCode {
+      super.writeByte(129)
+      super.writeValue(value.rawValue)
+    } else if let value = value as? PlatformConfigurationParams {
+      super.writeByte(130)
+      super.writeValue(value.toList())
+    } else if let value = value as? UserData {
+      super.writeByte(131)
+      super.writeValue(value.toList())
+    } else if let value = value as? SignInFailure {
+      super.writeByte(132)
+      super.writeValue(value.toList())
+    } else if let value = value as? SignInSuccess {
+      super.writeByte(133)
+      super.writeValue(value.toList())
+    } else {
+      super.writeValue(value)
+    }
+  }
+}
+
+private class MessagesPigeonCodecReaderWriter: FlutterStandardReaderWriter {
+  override func reader(with data: Data) -> FlutterStandardReader {
+    return MessagesPigeonCodecReader(data: data)
+  }
+
+  override func writer(with data: NSMutableData) -> FlutterStandardWriter {
+    return MessagesPigeonCodecWriter(data: data)
+  }
+}
+
+class MessagesPigeonCodec: FlutterStandardMessageCodec, @unchecked Sendable {
+  static let shared = MessagesPigeonCodec(readerWriter: MessagesPigeonCodecReaderWriter())
+}
+
+/// Generated protocol from Pigeon that represents a handler of messages from Flutter.
+protocol GoogleSignInApi {
+  /// Configures the sign in object with application-level parameters.
+  func configure(params: PlatformConfigurationParams) throws
+  /// Attempts to restore an existing sign-in, if any, with minimal user
+  /// interaction.
+  func restorePreviousSignIn(completion: @escaping (Result<SignInResult, Error>) -> Void)
+  /// Starts a sign in with user interaction.
+  func signIn(
+    scopeHint: [String], nonce: String?, completion: @escaping (Result<SignInResult, Error>) -> Void
+  )
+  /// Requests the access token for the current sign in.
+  func getRefreshedAuthorizationTokens(
+    userId: String, completion: @escaping (Result<SignInResult, Error>) -> Void)
+  /// Requests authorization of the given additional scopes.
+  func addScopes(
+    _ scopes: [String], forUser userId: String,
+    completion: @escaping (Result<SignInResult, Error>) -> Void)
+  /// Signs out the current user.
+  func signOut() throws
+  /// Revokes scope grants to the application.
+  func disconnect(completion: @escaping (Result<Void, Error>) -> Void)
+}
+
+/// Generated setup class from Pigeon to handle messages through the `binaryMessenger`.
+class GoogleSignInApiSetup {
+  static var codec: FlutterStandardMessageCodec { MessagesPigeonCodec.shared }
+  /// Sets up an instance of `GoogleSignInApi` to handle messages through the `binaryMessenger`.
+  static func setUp(
+    binaryMessenger: FlutterBinaryMessenger, api: GoogleSignInApi?,
+    messageChannelSuffix: String = ""
+  ) {
+    let channelSuffix = messageChannelSuffix.count > 0 ? ".\(messageChannelSuffix)" : ""
+    /// Configures the sign in object with application-level parameters.
+    let configureChannel = FlutterBasicMessageChannel(
+      name: "dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.configure\(channelSuffix)",
+      binaryMessenger: binaryMessenger, codec: codec)
+    if let api = api {
+      configureChannel.setMessageHandler { message, reply in
+        let args = message as! [Any?]
+        let paramsArg = args[0] as! PlatformConfigurationParams
+        do {
+          try api.configure(params: paramsArg)
+          reply(wrapResult(nil))
+        } catch {
+          reply(wrapError(error))
+        }
+      }
+    } else {
+      configureChannel.setMessageHandler(nil)
+    }
+    /// Attempts to restore an existing sign-in, if any, with minimal user
+    /// interaction.
+    let restorePreviousSignInChannel = FlutterBasicMessageChannel(
+      name:
+        "dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.restorePreviousSignIn\(channelSuffix)",
+      binaryMessenger: binaryMessenger, codec: codec)
+    if let api = api {
+      restorePreviousSignInChannel.setMessageHandler { _, reply in
+        api.restorePreviousSignIn { result in
+          switch result {
+          case .success(let res):
+            reply(wrapResult(res))
+          case .failure(let error):
+            reply(wrapError(error))
+          }
+        }
+      }
+    } else {
+      restorePreviousSignInChannel.setMessageHandler(nil)
+    }
+    /// Starts a sign in with user interaction.
+    let signInChannel = FlutterBasicMessageChannel(
+      name: "dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.signIn\(channelSuffix)",
+      binaryMessenger: binaryMessenger, codec: codec)
+    if let api = api {
+      signInChannel.setMessageHandler { message, reply in
+        let args = message as! [Any?]
+        let scopeHintArg = args[0] as! [String]
+        let nonceArg: String? = nilOrValue(args[1])
+        api.signIn(scopeHint: scopeHintArg, nonce: nonceArg) { result in
+          switch result {
+          case .success(let res):
+            reply(wrapResult(res))
+          case .failure(let error):
+            reply(wrapError(error))
+          }
+        }
+      }
+    } else {
+      signInChannel.setMessageHandler(nil)
+    }
+    /// Requests the access token for the current sign in.
+    let getRefreshedAuthorizationTokensChannel = FlutterBasicMessageChannel(
+      name:
+        "dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.getRefreshedAuthorizationTokens\(channelSuffix)",
+      binaryMessenger: binaryMessenger, codec: codec)
+    if let api = api {
+      getRefreshedAuthorizationTokensChannel.setMessageHandler { message, reply in
+        let args = message as! [Any?]
+        let userIdArg = args[0] as! String
+        api.getRefreshedAuthorizationTokens(userId: userIdArg) { result in
+          switch result {
+          case .success(let res):
+            reply(wrapResult(res))
+          case .failure(let error):
+            reply(wrapError(error))
+          }
+        }
+      }
+    } else {
+      getRefreshedAuthorizationTokensChannel.setMessageHandler(nil)
+    }
+    /// Requests authorization of the given additional scopes.
+    let addScopesChannel = FlutterBasicMessageChannel(
+      name: "dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.addScopes\(channelSuffix)",
+      binaryMessenger: binaryMessenger, codec: codec)
+    if let api = api {
+      addScopesChannel.setMessageHandler { message, reply in
+        let args = message as! [Any?]
+        let scopesArg = args[0] as! [String]
+        let userIdArg = args[1] as! String
+        api.addScopes(scopesArg, forUser: userIdArg) { result in
+          switch result {
+          case .success(let res):
+            reply(wrapResult(res))
+          case .failure(let error):
+            reply(wrapError(error))
+          }
+        }
+      }
+    } else {
+      addScopesChannel.setMessageHandler(nil)
+    }
+    /// Signs out the current user.
+    let signOutChannel = FlutterBasicMessageChannel(
+      name: "dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.signOut\(channelSuffix)",
+      binaryMessenger: binaryMessenger, codec: codec)
+    if let api = api {
+      signOutChannel.setMessageHandler { _, reply in
+        do {
+          try api.signOut()
+          reply(wrapResult(nil))
+        } catch {
+          reply(wrapError(error))
+        }
+      }
+    } else {
+      signOutChannel.setMessageHandler(nil)
+    }
+    /// Revokes scope grants to the application.
+    let disconnectChannel = FlutterBasicMessageChannel(
+      name: "dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.disconnect\(channelSuffix)",
+      binaryMessenger: binaryMessenger, codec: codec)
+    if let api = api {
+      disconnectChannel.setMessageHandler { _, reply in
+        api.disconnect { result in
+          switch result {
+          case .success:
+            reply(wrapResult(nil))
+          case .failure(let error):
+            reply(wrapError(error))
+          }
+        }
+      }
+    } else {
+      disconnectChannel.setMessageHandler(nil)
+    }
+  }
+}
diff --git a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios_objc/include/google_sign_in_ios/messages.g.h b/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios_objc/include/google_sign_in_ios/messages.g.h
deleted file mode 100644
index 8a42064cd2cc..000000000000
--- a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios_objc/include/google_sign_in_ios/messages.g.h
+++ /dev/null
@@ -1,165 +0,0 @@
-// Copyright 2013 The Flutter Authors
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-// Autogenerated from Pigeon (v27.3.2), do not edit directly.
-// See also: https://pub.dev/packages/pigeon
-
-@import Foundation;
-
-@protocol FlutterBinaryMessenger;
-@protocol FlutterMessageCodec;
-@class FlutterError;
-@class FlutterStandardTypedData;
-
-NS_ASSUME_NONNULL_BEGIN
-
-/// Enum mapping of known codes from
-/// https://developers.google.com/identity/sign-in/ios/reference/Enums/GIDSignInErrorCode
-typedef NS_ENUM(NSUInteger, FSIGoogleSignInErrorCode) {
-  /// Either the underlying kGIDSignInErrorCodeUnknown, or a code that isn't
-  /// a known code mapped to a value below.
-  FSIGoogleSignInErrorCodeUnknown = 0,
-  /// kGIDSignInErrorCodeKeychain; an error reading or writing to keychain.
-  FSIGoogleSignInErrorCodeKeychainError = 1,
-  /// kGIDSignInErrorCodeHasNoAuthInKeychain; no auth present in the keychain.
-  ///
-  /// For restorePreviousSignIn, this indicates that there is no sign in to
-  /// restore.
-  FSIGoogleSignInErrorCodeNoAuthInKeychain = 2,
-  /// kGIDSignInErrorCodeCanceled; the request was canceled by the user.
-  FSIGoogleSignInErrorCodeCanceled = 3,
-  /// kGIDSignInErrorCodeEMM; an enterprise management error occurred.
-  FSIGoogleSignInErrorCodeEemError = 4,
-  /// kGIDSignInErrorCodeScopesAlreadyGranted; the requested scopes have already
-  /// been granted.
-  FSIGoogleSignInErrorCodeScopesAlreadyGranted = 5,
-  /// kGIDSignInErrorCodeMismatchWithCurrentUser; an operation was requested on
-  /// a non-current user.
-  FSIGoogleSignInErrorCodeUserMismatch = 6,
-};
-
-/// Wrapper for FSIGoogleSignInErrorCode to allow for nullability.
-@interface FSIGoogleSignInErrorCodeBox : NSObject
-@property(nonatomic, assign) FSIGoogleSignInErrorCode value;
-- (instancetype)initWithValue:(FSIGoogleSignInErrorCode)value;
-@end
-
-@class FSIPlatformConfigurationParams;
-@class FSIUserData;
-@class FSISignInResult;
-@class FSISignInFailure;
-@class FSISignInSuccess;
-
-@interface FSIPlatformConfigurationParams : NSObject
-+ (instancetype)makeWithClientId:(nullable NSString *)clientId
-                  serverClientId:(nullable NSString *)serverClientId
-                    hostedDomain:(nullable NSString *)hostedDomain;
-@property(nonatomic, copy, nullable) NSString *clientId;
-@property(nonatomic, copy, nullable) NSString *serverClientId;
-@property(nonatomic, copy, nullable) NSString *hostedDomain;
-@end
-
-/// Pigeon version of GoogleSignInUserData + AuthenticationTokenData.
-///
-/// See GoogleSignInUserData and AuthenticationTokenData for details.
-@interface FSIUserData : NSObject
-/// `init` unavailable to enforce nonnull fields, see the `make` class method.
-- (instancetype)init NS_UNAVAILABLE;
-+ (instancetype)makeWithDisplayName:(nullable NSString *)displayName
-                              email:(NSString *)email
-                             userId:(NSString *)userId
-                           photoUrl:(nullable NSString *)photoUrl
-                            idToken:(nullable NSString *)idToken;
-@property(nonatomic, copy, nullable) NSString *displayName;
-@property(nonatomic, copy) NSString *email;
-@property(nonatomic, copy) NSString *userId;
-@property(nonatomic, copy, nullable) NSString *photoUrl;
-@property(nonatomic, copy, nullable) NSString *idToken;
-@end
-
-/// The response from an auth call.
-@interface FSISignInResult : NSObject
-+ (instancetype)makeWithSuccess:(nullable FSISignInSuccess *)success
-                          error:(nullable FSISignInFailure *)error;
-/// The success result, if any.
-///
-/// Exactly one of success and error will be non-nil.
-@property(nonatomic, strong, nullable) FSISignInSuccess *success;
-/// The error result, if any.
-///
-/// Exactly one of success and error will be non-nil.
-@property(nonatomic, strong, nullable) FSISignInFailure *error;
-@end
-
-/// An sign in failure.
-@interface FSISignInFailure : NSObject
-/// `init` unavailable to enforce nonnull fields, see the `make` class method.
-- (instancetype)init NS_UNAVAILABLE;
-+ (instancetype)makeWithType:(FSIGoogleSignInErrorCode)type
-                     message:(nullable NSString *)message
-                     details:(nullable id)details;
-/// The type of failure.
-@property(nonatomic, assign) FSIGoogleSignInErrorCode type;
-/// The message associated with the failure, if any.
-@property(nonatomic, copy, nullable) NSString *message;
-/// Extra details about the failure, if any.
-@property(nonatomic, strong, nullable) id details;
-@end
-
-/// A successful auth result.
-///
-/// Corresponds to the information in a native GIDSignInResult. Because of the
-/// structure of the Google Sign In SDK, this has information corresponding to
-/// both authn and authz steps, even though incremental authorization is
-/// supported.
-@interface FSISignInSuccess : NSObject
-/// `init` unavailable to enforce nonnull fields, see the `make` class method.
-- (instancetype)init NS_UNAVAILABLE;
-+ (instancetype)makeWithUser:(FSIUserData *)user
-                 accessToken:(NSString *)accessToken
-               grantedScopes:(NSArray<NSString *> *)grantedScopes
-              serverAuthCode:(nullable NSString *)serverAuthCode;
-@property(nonatomic, strong) FSIUserData *user;
-@property(nonatomic, copy) NSString *accessToken;
-@property(nonatomic, copy) NSArray<NSString *> *grantedScopes;
-@property(nonatomic, copy, nullable) NSString *serverAuthCode;
-@end
-
-/// The codec used by all APIs.
-NSObject<FlutterMessageCodec> *FSIGetMessagesCodec(void);
-
-@protocol FSIGoogleSignInApi
-/// Configures the sign in object with application-level parameters.
-- (void)configureWithParameters:(FSIPlatformConfigurationParams *)params
-                          error:(FlutterError *_Nullable *_Nonnull)error;
-/// Attempts to restore an existing sign-in, if any, with minimal user
-/// interaction.
-- (void)restorePreviousSignInWithCompletion:(void (^)(FSISignInResult *_Nullable,
-                                                      FlutterError *_Nullable))completion;
-/// Starts a sign in with user interaction.
-- (void)signInWithScopeHint:(NSArray<NSString *> *)scopeHint
-                      nonce:(nullable NSString *)nonce
-                 completion:
-                     (void (^)(FSISignInResult *_Nullable, FlutterError *_Nullable))completion;
-/// Requests the access token for the current sign in.
-- (void)refreshedAuthorizationTokensForUser:(NSString *)userId
-                                 completion:(void (^)(FSISignInResult *_Nullable,
-                                                      FlutterError *_Nullable))completion;
-/// Requests authorization of the given additional scopes.
-- (void)addScopes:(NSArray<NSString *> *)scopes
-          forUser:(NSString *)userId
-       completion:(void (^)(FSISignInResult *_Nullable, FlutterError *_Nullable))completion;
-/// Signs out the current user.
-- (void)signOutWithError:(FlutterError *_Nullable *_Nonnull)error;
-/// Revokes scope grants to the application.
-- (void)disconnectWithCompletion:(void (^)(FlutterError *_Nullable))completion;
-@end
-
-extern void SetUpFSIGoogleSignInApi(id<FlutterBinaryMessenger> binaryMessenger,
-                                    NSObject<FSIGoogleSignInApi> *_Nullable api);
-
-extern void SetUpFSIGoogleSignInApiWithSuffix(id<FlutterBinaryMessenger> binaryMessenger,
-                                              NSObject<FSIGoogleSignInApi> *_Nullable api,
-                                              NSString *messageChannelSuffix);
-
-NS_ASSUME_NONNULL_END
diff --git a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios_objc/messages.g.m b/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios_objc/messages.g.m
deleted file mode 100644
index 21a8e10bc3af..000000000000
--- a/packages/google_sign_in/google_sign_in_ios/darwin/google_sign_in_ios/Sources/google_sign_in_ios_objc/messages.g.m
+++ /dev/null
@@ -1,718 +0,0 @@
-// Copyright 2013 The Flutter Authors
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-// Autogenerated from Pigeon (v27.3.2), do not edit directly.
-// See also: https://pub.dev/packages/pigeon
-
-#import "./include/google_sign_in_ios/messages.g.h"
-
-#if TARGET_OS_OSX
-@import FlutterMacOS;
-#else
-@import Flutter;
-#endif
-
-static BOOL __attribute__((unused)) FLTPigeonDeepEquals(id _Nullable a, id _Nullable b) {
-  if (a == b) {
-    return YES;
-  }
-  if (a == nil) {
-    return b == [NSNull null];
-  }
-  if (b == nil) {
-    return a == [NSNull null];
-  }
-  if ([a isKindOfClass:[NSNumber class]] && [b isKindOfClass:[NSNumber class]]) {
-    return
-        [a isEqual:b] || (isnan([(NSNumber *)a doubleValue]) && isnan([(NSNumber *)b doubleValue]));
-  }
-  if ([a isKindOfClass:[NSArray class]] && [b isKindOfClass:[NSArray class]]) {
-    NSArray *arrayA = (NSArray *)a;
-    NSArray *arrayB = (NSArray *)b;
-    if (arrayA.count != arrayB.count) {
-      return NO;
-    }
-    for (NSUInteger i = 0; i < arrayA.count; i++) {
-      if (!FLTPigeonDeepEquals(arrayA[i], arrayB[i])) {
-        return NO;
-      }
-    }
-    return YES;
-  }
-  if ([a isKindOfClass:[NSDictionary class]] && [b isKindOfClass:[NSDictionary class]]) {
-    NSDictionary *dictA = (NSDictionary *)a;
-    NSDictionary *dictB = (NSDictionary *)b;
-    if (dictA.count != dictB.count) {
-      return NO;
-    }
-    for (id keyA in dictA) {
-      id valueA = dictA[keyA];
-      BOOL found = NO;
-      for (id keyB in dictB) {
-        if (FLTPigeonDeepEquals(keyA, keyB)) {
-          id valueB = dictB[keyB];
-          if (FLTPigeonDeepEquals(valueA, valueB)) {
-            found = YES;
-            break;
-          } else {
-            return NO;
-          }
-        }
-      }
-      if (!found) {
-        return NO;
-      }
-    }
-    return YES;
-  }
-  return [a isEqual:b];
-}
-
-static NSUInteger __attribute__((unused)) FLTPigeonDeepHash(id _Nullable value) {
-  if (value == nil || value == (id)[NSNull null]) {
-    return 0;
-  }
-  if ([value isKindOfClass:[NSNumber class]]) {
-    NSNumber *n = (NSNumber *)value;
-    double d = n.doubleValue;
-    if (isnan(d)) {
-      // Normalize NaN to a consistent hash.
-      return (NSUInteger)0x7FF8000000000000;
-    }
-    if (d == 0.0) {
-      // Normalize -0.0 to 0.0 so they have the same hash code.
-      d = 0.0;
-    }
-    return @(d).hash;
-  }
-  if ([value isKindOfClass:[NSArray class]]) {
-    NSUInteger result = 1;
-    for (id item in (NSArray *)value) {
-      result = result * 31 + FLTPigeonDeepHash(item);
-    }
-    return result;
-  }
-  if ([value isKindOfClass:[NSDictionary class]]) {
-    NSUInteger result = 0;
-    NSDictionary *dict = (NSDictionary *)value;
-    for (id key in dict) {
-      result += ((FLTPigeonDeepHash(key) * 31) ^ FLTPigeonDeepHash(dict[key]));
-    }
-    return result;
-  }
-  return [value hash];
-}
-
-static NSArray<id> *wrapResult(id result, FlutterError *error) {
-  if (error) {
-    return @[
-      error.code ?: [NSNull null], error.message ?: [NSNull null], error.details ?: [NSNull null]
-    ];
-  }
-  return @[ result ?: [NSNull null] ];
-}
-
-static id GetNullableObjectAtIndex(NSArray<id> *array, NSInteger key) {
-  id result = array[key];
-  return (result == [NSNull null]) ? nil : result;
-}
-
-/// Enum mapping of known codes from
-/// https://developers.google.com/identity/sign-in/ios/reference/Enums/GIDSignInErrorCode
-@implementation FSIGoogleSignInErrorCodeBox
-- (instancetype)initWithValue:(FSIGoogleSignInErrorCode)value {
-  self = [super init];
-  if (self) {
-    _value = value;
-  }
-  return self;
-}
-@end
-
-@interface FSIPlatformConfigurationParams ()
-+ (FSIPlatformConfigurationParams *)fromList:(NSArray<id> *)list;
-+ (nullable FSIPlatformConfigurationParams *)nullableFromList:(NSArray<id> *)list;
-- (NSArray<id> *)toList;
-@end
-
-@interface FSIUserData ()
-+ (FSIUserData *)fromList:(NSArray<id> *)list;
-+ (nullable FSIUserData *)nullableFromList:(NSArray<id> *)list;
-- (NSArray<id> *)toList;
-@end
-
-@interface FSISignInResult ()
-+ (FSISignInResult *)fromList:(NSArray<id> *)list;
-+ (nullable FSISignInResult *)nullableFromList:(NSArray<id> *)list;
-- (NSArray<id> *)toList;
-@end
-
-@interface FSISignInFailure ()
-+ (FSISignInFailure *)fromList:(NSArray<id> *)list;
-+ (nullable FSISignInFailure *)nullableFromList:(NSArray<id> *)list;
-- (NSArray<id> *)toList;
-@end
-
-@interface FSISignInSuccess ()
-+ (FSISignInSuccess *)fromList:(NSArray<id> *)list;
-+ (nullable FSISignInSuccess *)nullableFromList:(NSArray<id> *)list;
-- (NSArray<id> *)toList;
-@end
-
-@implementation FSIPlatformConfigurationParams
-+ (instancetype)makeWithClientId:(nullable NSString *)clientId
-                  serverClientId:(nullable NSString *)serverClientId
-                    hostedDomain:(nullable NSString *)hostedDomain {
-  FSIPlatformConfigurationParams *pigeonResult = [[FSIPlatformConfigurationParams alloc] init];
-  pigeonResult.clientId = clientId;
-  pigeonResult.serverClientId = serverClientId;
-  pigeonResult.hostedDomain = hostedDomain;
-  return pigeonResult;
-}
-+ (FSIPlatformConfigurationParams *)fromList:(NSArray<id> *)list {
-  FSIPlatformConfigurationParams *pigeonResult = [[FSIPlatformConfigurationParams alloc] init];
-  pigeonResult.clientId = GetNullableObjectAtIndex(list, 0);
-  pigeonResult.serverClientId = GetNullableObjectAtIndex(list, 1);
-  pigeonResult.hostedDomain = GetNullableObjectAtIndex(list, 2);
-  return pigeonResult;
-}
-+ (nullable FSIPlatformConfigurationParams *)nullableFromList:(NSArray<id> *)list {
-  return (list) ? [FSIPlatformConfigurationParams fromList:list] : nil;
-}
-- (NSArray<id> *)toList {
-  return @[
-    self.clientId ?: [NSNull null],
-    self.serverClientId ?: [NSNull null],
-    self.hostedDomain ?: [NSNull null],
-  ];
-}
-- (BOOL)isEqual:(id)object {
-  if (self == object) {
-    return YES;
-  }
-  if (![object isKindOfClass:[self class]]) {
-    return NO;
-  }
-  FSIPlatformConfigurationParams *other = (FSIPlatformConfigurationParams *)object;
-  return FLTPigeonDeepEquals(self.clientId, other.clientId) &&
-         FLTPigeonDeepEquals(self.serverClientId, other.serverClientId) &&
-         FLTPigeonDeepEquals(self.hostedDomain, other.hostedDomain);
-}
-
-- (NSUInteger)hash {
-  NSUInteger result = [self class].hash;
-  result = result * 31 + FLTPigeonDeepHash(self.clientId);
-  result = result * 31 + FLTPigeonDeepHash(self.serverClientId);
-  result = result * 31 + FLTPigeonDeepHash(self.hostedDomain);
-  return result;
-}
-- (NSString *)description {
-  return [NSString
-      stringWithFormat:
-          @"FSIPlatformConfigurationParams(clientId: %@, serverClientId: %@, hostedDomain: %@)",
-          self.clientId, self.serverClientId, self.hostedDomain];
-}
-@end
-
-@implementation FSIUserData
-+ (instancetype)makeWithDisplayName:(nullable NSString *)displayName
-                              email:(NSString *)email
-                             userId:(NSString *)userId
-                           photoUrl:(nullable NSString *)photoUrl
-                            idToken:(nullable NSString *)idToken {
-  FSIUserData *pigeonResult = [[FSIUserData alloc] init];
-  pigeonResult.displayName = displayName;
-  pigeonResult.email = email;
-  pigeonResult.userId = userId;
-  pigeonResult.photoUrl = photoUrl;
-  pigeonResult.idToken = idToken;
-  return pigeonResult;
-}
-+ (FSIUserData *)fromList:(NSArray<id> *)list {
-  FSIUserData *pigeonResult = [[FSIUserData alloc] init];
-  pigeonResult.displayName = GetNullableObjectAtIndex(list, 0);
-  pigeonResult.email = GetNullableObjectAtIndex(list, 1);
-  pigeonResult.userId = GetNullableObjectAtIndex(list, 2);
-  pigeonResult.photoUrl = GetNullableObjectAtIndex(list, 3);
-  pigeonResult.idToken = GetNullableObjectAtIndex(list, 4);
-  return pigeonResult;
-}
-+ (nullable FSIUserData *)nullableFromList:(NSArray<id> *)list {
-  return (list) ? [FSIUserData fromList:list] : nil;
-}
-- (NSArray<id> *)toList {
-  return @[
-    self.displayName ?: [NSNull null],
-    self.email ?: [NSNull null],
-    self.userId ?: [NSNull null],
-    self.photoUrl ?: [NSNull null],
-    self.idToken ?: [NSNull null],
-  ];
-}
-- (BOOL)isEqual:(id)object {
-  if (self == object) {
-    return YES;
-  }
-  if (![object isKindOfClass:[self class]]) {
-    return NO;
-  }
-  FSIUserData *other = (FSIUserData *)object;
-  return FLTPigeonDeepEquals(self.displayName, other.displayName) &&
-         FLTPigeonDeepEquals(self.email, other.email) &&
-         FLTPigeonDeepEquals(self.userId, other.userId) &&
-         FLTPigeonDeepEquals(self.photoUrl, other.photoUrl) &&
-         FLTPigeonDeepEquals(self.idToken, other.idToken);
-}
-
-- (NSUInteger)hash {
-  NSUInteger result = [self class].hash;
-  result = result * 31 + FLTPigeonDeepHash(self.displayName);
-  result = result * 31 + FLTPigeonDeepHash(self.email);
-  result = result * 31 + FLTPigeonDeepHash(self.userId);
-  result = result * 31 + FLTPigeonDeepHash(self.photoUrl);
-  result = result * 31 + FLTPigeonDeepHash(self.idToken);
-  return result;
-}
-- (NSString *)description {
-  return [NSString
-      stringWithFormat:
-          @"FSIUserData(displayName: %@, email: %@, userId: %@, photoUrl: %@, idToken: %@)",
-          self.displayName, self.email, self.userId, self.photoUrl, self.idToken];
-}
-@end
-
-@implementation FSISignInResult
-+ (instancetype)makeWithSuccess:(nullable FSISignInSuccess *)success
-                          error:(nullable FSISignInFailure *)error {
-  FSISignInResult *pigeonResult = [[FSISignInResult alloc] init];
-  pigeonResult.success = success;
-  pigeonResult.error = error;
-  return pigeonResult;
-}
-+ (FSISignInResult *)fromList:(NSArray<id> *)list {
-  FSISignInResult *pigeonResult = [[FSISignInResult alloc] init];
-  pigeonResult.success = GetNullableObjectAtIndex(list, 0);
-  pigeonResult.error = GetNullableObjectAtIndex(list, 1);
-  return pigeonResult;
-}
-+ (nullable FSISignInResult *)nullableFromList:(NSArray<id> *)list {
-  return (list) ? [FSISignInResult fromList:list] : nil;
-}
-- (NSArray<id> *)toList {
-  return @[
-    self.success ?: [NSNull null],
-    self.error ?: [NSNull null],
-  ];
-}
-- (BOOL)isEqual:(id)object {
-  if (self == object) {
-    return YES;
-  }
-  if (![object isKindOfClass:[self class]]) {
-    return NO;
-  }
-  FSISignInResult *other = (FSISignInResult *)object;
-  return FLTPigeonDeepEquals(self.success, other.success) &&
-         FLTPigeonDeepEquals(self.error, other.error);
-}
-
-- (NSUInteger)hash {
-  NSUInteger result = [self class].hash;
-  result = result * 31 + FLTPigeonDeepHash(self.success);
-  result = result * 31 + FLTPigeonDeepHash(self.error);
-  return result;
-}
-- (NSString *)description {
-  return [NSString
-      stringWithFormat:@"FSISignInResult(success: %@, error: %@)", self.success, self.error];
-}
-@end
-
-@implementation FSISignInFailure
-+ (instancetype)makeWithType:(FSIGoogleSignInErrorCode)type
-                     message:(nullable NSString *)message
-                     details:(nullable id)details {
-  FSISignInFailure *pigeonResult = [[FSISignInFailure alloc] init];
-  pigeonResult.type = type;
-  pigeonResult.message = message;
-  pigeonResult.details = details;
-  return pigeonResult;
-}
-+ (FSISignInFailure *)fromList:(NSArray<id> *)list {
-  FSISignInFailure *pigeonResult = [[FSISignInFailure alloc] init];
-  FSIGoogleSignInErrorCodeBox *boxedFSIGoogleSignInErrorCode = GetNullableObjectAtIndex(list, 0);
-  pigeonResult.type = boxedFSIGoogleSignInErrorCode.value;
-  pigeonResult.message = GetNullableObjectAtIndex(list, 1);
-  pigeonResult.details = GetNullableObjectAtIndex(list, 2);
-  return pigeonResult;
-}
-+ (nullable FSISignInFailure *)nullableFromList:(NSArray<id> *)list {
-  return (list) ? [FSISignInFailure fromList:list] : nil;
-}
-- (NSArray<id> *)toList {
-  return @[
-    [[FSIGoogleSignInErrorCodeBox alloc] initWithValue:self.type],
-    self.message ?: [NSNull null],
-    self.details ?: [NSNull null],
-  ];
-}
-- (BOOL)isEqual:(id)object {
-  if (self == object) {
-    return YES;
-  }
-  if (![object isKindOfClass:[self class]]) {
-    return NO;
-  }
-  FSISignInFailure *other = (FSISignInFailure *)object;
-  return self.type == other.type && FLTPigeonDeepEquals(self.message, other.message) &&
-         FLTPigeonDeepEquals(self.details, other.details);
-}
-
-- (NSUInteger)hash {
-  NSUInteger result = [self class].hash;
-  result = result * 31 + @(self.type).hash;
-  result = result * 31 + FLTPigeonDeepHash(self.message);
-  result = result * 31 + FLTPigeonDeepHash(self.details);
-  return result;
-}
-- (NSString *)description {
-  return [NSString stringWithFormat:@"FSISignInFailure(type: %ld, message: %@, details: %@)",
-                                    (long)self.type, self.message, self.details];
-}
-@end
-
-@implementation FSISignInSuccess
-+ (instancetype)makeWithUser:(FSIUserData *)user
-                 accessToken:(NSString *)accessToken
-               grantedScopes:(NSArray<NSString *> *)grantedScopes
-              serverAuthCode:(nullable NSString *)serverAuthCode {
-  FSISignInSuccess *pigeonResult = [[FSISignInSuccess alloc] init];
-  pigeonResult.user = user;
-  pigeonResult.accessToken = accessToken;
-  pigeonResult.grantedScopes = grantedScopes;
-  pigeonResult.serverAuthCode = serverAuthCode;
-  return pigeonResult;
-}
-+ (FSISignInSuccess *)fromList:(NSArray<id> *)list {
-  FSISignInSuccess *pigeonResult = [[FSISignInSuccess alloc] init];
-  pigeonResult.user = GetNullableObjectAtIndex(list, 0);
-  pigeonResult.accessToken = GetNullableObjectAtIndex(list, 1);
-  pigeonResult.grantedScopes = GetNullableObjectAtIndex(list, 2);
-  pigeonResult.serverAuthCode = GetNullableObjectAtIndex(list, 3);
-  return pigeonResult;
-}
-+ (nullable FSISignInSuccess *)nullableFromList:(NSArray<id> *)list {
-  return (list) ? [FSISignInSuccess fromList:list] : nil;
-}
-- (NSArray<id> *)toList {
-  return @[
-    self.user ?: [NSNull null],
-    self.accessToken ?: [NSNull null],
-    self.grantedScopes ?: [NSNull null],
-    self.serverAuthCode ?: [NSNull null],
-  ];
-}
-- (BOOL)isEqual:(id)object {
-  if (self == object) {
-    return YES;
-  }
-  if (![object isKindOfClass:[self class]]) {
-    return NO;
-  }
-  FSISignInSuccess *other = (FSISignInSuccess *)object;
-  return FLTPigeonDeepEquals(self.user, other.user) &&
-         FLTPigeonDeepEquals(self.accessToken, other.accessToken) &&
-         FLTPigeonDeepEquals(self.grantedScopes, other.grantedScopes) &&
-         FLTPigeonDeepEquals(self.serverAuthCode, other.serverAuthCode);
-}
-
-- (NSUInteger)hash {
-  NSUInteger result = [self class].hash;
-  result = result * 31 + FLTPigeonDeepHash(self.user);
-  result = result * 31 + FLTPigeonDeepHash(self.accessToken);
-  result = result * 31 + FLTPigeonDeepHash(self.grantedScopes);
-  result = result * 31 + FLTPigeonDeepHash(self.serverAuthCode);
-  return result;
-}
-- (NSString *)description {
-  return [NSString
-      stringWithFormat:
-          @"FSISignInSuccess(user: %@, accessToken: %@, grantedScopes: %@, serverAuthCode: %@)",
-          self.user, self.accessToken, self.grantedScopes, self.serverAuthCode];
-}
-@end
-
-@interface FSIMessagesPigeonCodecReader : FlutterStandardReader
-@end
-@implementation FSIMessagesPigeonCodecReader
-- (nullable id)readValueOfType:(UInt8)type {
-  switch (type) {
-    case 129: {
-      NSNumber *enumAsNumber = [self readValue];
-      return enumAsNumber == nil
-                 ? nil
-                 : [[FSIGoogleSignInErrorCodeBox alloc] initWithValue:[enumAsNumber integerValue]];
-    }
-    case 130:
-      return [FSIPlatformConfigurationParams fromList:[self readValue]];
-    case 131:
-      return [FSIUserData fromList:[self readValue]];
-    case 132:
-      return [FSISignInResult fromList:[self readValue]];
-    case 133:
-      return [FSISignInFailure fromList:[self readValue]];
-    case 134:
-      return [FSISignInSuccess fromList:[self readValue]];
-    default:
-      return [super readValueOfType:type];
-  }
-}
-@end
-
-@interface FSIMessagesPigeonCodecWriter : FlutterStandardWriter
-@end
-@implementation FSIMessagesPigeonCodecWriter
-- (void)writeValue:(id)value {
-  if ([value isKindOfClass:[FSIGoogleSignInErrorCodeBox class]]) {
-    FSIGoogleSignInErrorCodeBox *box = (FSIGoogleSignInErrorCodeBox *)value;
-    [self writeByte:129];
-    [self writeValue:(value == nil ? [NSNull null] : [NSNumber numberWithInteger:box.value])];
-  } else if ([value isKindOfClass:[FSIPlatformConfigurationParams class]]) {
-    [self writeByte:130];
-    [self writeValue:[value toList]];
-  } else if ([value isKindOfClass:[FSIUserData class]]) {
-    [self writeByte:131];
-    [self writeValue:[value toList]];
-  } else if ([value isKindOfClass:[FSISignInResult class]]) {
-    [self writeByte:132];
-    [self writeValue:[value toList]];
-  } else if ([value isKindOfClass:[FSISignInFailure class]]) {
-    [self writeByte:133];
-    [self writeValue:[value toList]];
-  } else if ([value isKindOfClass:[FSISignInSuccess class]]) {
-    [self writeByte:134];
-    [self writeValue:[value toList]];
-  } else {
-    [super writeValue:value];
-  }
-}
-@end
-
-@interface FSIMessagesPigeonCodecReaderWriter : FlutterStandardReaderWriter
-@end
-@implementation FSIMessagesPigeonCodecReaderWriter
-- (FlutterStandardWriter *)writerWithData:(NSMutableData *)data {
-  return [[FSIMessagesPigeonCodecWriter alloc] initWithData:data];
-}
-- (FlutterStandardReader *)readerWithData:(NSData *)data {
-  return [[FSIMessagesPigeonCodecReader alloc] initWithData:data];
-}
-@end
-
-NSObject<FlutterMessageCodec> *FSIGetMessagesCodec(void) {
-  static FlutterStandardMessageCodec *sSharedObject = nil;
-  static dispatch_once_t sPred = 0;
-  dispatch_once(&sPred, ^{
-    FSIMessagesPigeonCodecReaderWriter *readerWriter =
-        [[FSIMessagesPigeonCodecReaderWriter alloc] init];
-    sSharedObject = [FlutterStandardMessageCodec codecWithReaderWriter:readerWriter];
-  });
-  return sSharedObject;
-}
-void SetUpFSIGoogleSignInApi(id<FlutterBinaryMessenger> binaryMessenger,
-                             NSObject<FSIGoogleSignInApi> *api) {
-  SetUpFSIGoogleSignInApiWithSuffix(binaryMessenger, api, @"");
-}
-
-void SetUpFSIGoogleSignInApiWithSuffix(id<FlutterBinaryMessenger> binaryMessenger,
-                                       NSObject<FSIGoogleSignInApi> *api,
-                                       NSString *messageChannelSuffix) {
-  messageChannelSuffix = messageChannelSuffix.length > 0
-                             ? [NSString stringWithFormat:@".%@", messageChannelSuffix]
-                             : @"";
-  /// Configures the sign in object with application-level parameters.
-  {
-    FlutterBasicMessageChannel *channel = [[FlutterBasicMessageChannel alloc]
-           initWithName:[NSString
-                            stringWithFormat:
-                                @"%@%@",
-                                @"dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.configure",
-                                messageChannelSuffix]
-        binaryMessenger:binaryMessenger
-                  codec:FSIGetMessagesCodec()];
-    if (api) {
-      NSCAssert([api respondsToSelector:@selector(configureWithParameters:error:)],
-                @"FSIGoogleSignInApi api (%@) doesn't respond to "
-                @"@selector(configureWithParameters:error:)",
-                api);
-      [channel setMessageHandler:^(id _Nullable message, FlutterReply callback) {
-        NSArray<id> *args = message;
-        FSIPlatformConfigurationParams *arg_params = GetNullableObjectAtIndex(args, 0);
-        FlutterError *error;
-        [api configureWithParameters:arg_params error:&error];
-        callback(wrapResult(nil, error));
-      }];
-    } else {
-      [channel setMessageHandler:nil];
-    }
-  }
-  /// Attempts to restore an existing sign-in, if any, with minimal user
-  /// interaction.
-  {
-    FlutterBasicMessageChannel *channel = [[FlutterBasicMessageChannel alloc]
-           initWithName:[NSString stringWithFormat:@"%@%@",
-                                                   @"dev.flutter.pigeon.google_sign_in_ios."
-                                                   @"GoogleSignInApi.restorePreviousSignIn",
-                                                   messageChannelSuffix]
-        binaryMessenger:binaryMessenger
-                  codec:FSIGetMessagesCodec()];
-    if (api) {
-      NSCAssert([api respondsToSelector:@selector(restorePreviousSignInWithCompletion:)],
-                @"FSIGoogleSignInApi api (%@) doesn't respond to "
-                @"@selector(restorePreviousSignInWithCompletion:)",
-                api);
-      [channel setMessageHandler:^(id _Nullable message, FlutterReply callback) {
-        [api restorePreviousSignInWithCompletion:^(FSISignInResult *_Nullable output,
-                                                   FlutterError *_Nullable error) {
-          callback(wrapResult(output, error));
-        }];
-      }];
-    } else {
-      [channel setMessageHandler:nil];
-    }
-  }
-  /// Starts a sign in with user interaction.
-  {
-    FlutterBasicMessageChannel *channel = [[FlutterBasicMessageChannel alloc]
-           initWithName:
-               [NSString
-                   stringWithFormat:@"%@%@",
-                                    @"dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.signIn",
-                                    messageChannelSuffix]
-        binaryMessenger:binaryMessenger
-                  codec:FSIGetMessagesCodec()];
-    if (api) {
-      NSCAssert([api respondsToSelector:@selector(signInWithScopeHint:nonce:completion:)],
-                @"FSIGoogleSignInApi api (%@) doesn't respond to "
-                @"@selector(signInWithScopeHint:nonce:completion:)",
-                api);
-      [channel setMessageHandler:^(id _Nullable message, FlutterReply callback) {
-        NSArray<id> *args = message;
-        NSArray<NSString *> *arg_scopeHint = GetNullableObjectAtIndex(args, 0);
-        NSString *arg_nonce = GetNullableObjectAtIndex(args, 1);
-        [api signInWithScopeHint:arg_scopeHint
-                           nonce:arg_nonce
-                      completion:^(FSISignInResult *_Nullable output,
-                                   FlutterError *_Nullable error) {
-                        callback(wrapResult(output, error));
-                      }];
-      }];
-    } else {
-      [channel setMessageHandler:nil];
-    }
-  }
-  /// Requests the access token for the current sign in.
-  {
-    FlutterBasicMessageChannel *channel = [[FlutterBasicMessageChannel alloc]
-           initWithName:[NSString
-                            stringWithFormat:@"%@%@",
-                                             @"dev.flutter.pigeon.google_sign_in_ios."
-                                             @"GoogleSignInApi.getRefreshedAuthorizationTokens",
-                                             messageChannelSuffix]
-        binaryMessenger:binaryMessenger
-                  codec:FSIGetMessagesCodec()];
-    if (api) {
-      NSCAssert([api respondsToSelector:@selector(refreshedAuthorizationTokensForUser:completion:)],
-                @"FSIGoogleSignInApi api (%@) doesn't respond to "
-                @"@selector(refreshedAuthorizationTokensForUser:completion:)",
-                api);
-      [channel setMessageHandler:^(id _Nullable message, FlutterReply callback) {
-        NSArray<id> *args = message;
-        NSString *arg_userId = GetNullableObjectAtIndex(args, 0);
-        [api refreshedAuthorizationTokensForUser:arg_userId
-                                      completion:^(FSISignInResult *_Nullable output,
-                                                   FlutterError *_Nullable error) {
-                                        callback(wrapResult(output, error));
-                                      }];
-      }];
-    } else {
-      [channel setMessageHandler:nil];
-    }
-  }
-  /// Requests authorization of the given additional scopes.
-  {
-    FlutterBasicMessageChannel *channel = [[FlutterBasicMessageChannel alloc]
-           initWithName:[NSString
-                            stringWithFormat:
-                                @"%@%@",
-                                @"dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.addScopes",
-                                messageChannelSuffix]
-        binaryMessenger:binaryMessenger
-                  codec:FSIGetMessagesCodec()];
-    if (api) {
-      NSCAssert([api respondsToSelector:@selector(addScopes:forUser:completion:)],
-                @"FSIGoogleSignInApi api (%@) doesn't respond to "
-                @"@selector(addScopes:forUser:completion:)",
-                api);
-      [channel setMessageHandler:^(id _Nullable message, FlutterReply callback) {
-        NSArray<id> *args = message;
-        NSArray<NSString *> *arg_scopes = GetNullableObjectAtIndex(args, 0);
-        NSString *arg_userId = GetNullableObjectAtIndex(args, 1);
-        [api addScopes:arg_scopes
-               forUser:arg_userId
-            completion:^(FSISignInResult *_Nullable output, FlutterError *_Nullable error) {
-              callback(wrapResult(output, error));
-            }];
-      }];
-    } else {
-      [channel setMessageHandler:nil];
-    }
-  }
-  /// Signs out the current user.
-  {
-    FlutterBasicMessageChannel *channel = [[FlutterBasicMessageChannel alloc]
-           initWithName:[NSString
-                            stringWithFormat:
-                                @"%@%@",
-                                @"dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.signOut",
-                                messageChannelSuffix]
-        binaryMessenger:binaryMessenger
-                  codec:FSIGetMessagesCodec()];
-    if (api) {
-      NSCAssert([api respondsToSelector:@selector(signOutWithError:)],
-                @"FSIGoogleSignInApi api (%@) doesn't respond to @selector(signOutWithError:)",
-                api);
-      [channel setMessageHandler:^(id _Nullable message, FlutterReply callback) {
-        FlutterError *error;
-        [api signOutWithError:&error];
-        callback(wrapResult(nil, error));
-      }];
-    } else {
-      [channel setMessageHandler:nil];
-    }
-  }
-  /// Revokes scope grants to the application.
-  {
-    FlutterBasicMessageChannel *channel = [[FlutterBasicMessageChannel alloc]
-           initWithName:[NSString
-                            stringWithFormat:
-                                @"%@%@",
-                                @"dev.flutter.pigeon.google_sign_in_ios.GoogleSignInApi.disconnect",
-                                messageChannelSuffix]
-        binaryMessenger:binaryMessenger
-                  codec:FSIGetMessagesCodec()];
-    if (api) {
-      NSCAssert(
-          [api respondsToSelector:@selector(disconnectWithCompletion:)],
-          @"FSIGoogleSignInApi api (%@) doesn't respond to @selector(disconnectWithCompletion:)",
-          api);
-      [channel setMessageHandler:^(id _Nullable message, FlutterReply callback) {
-        [api disconnectWithCompletion:^(FlutterError *_Nullable error) {
-          callback(wrapResult(nil, error));
-        }];
-      }];
-    } else {
-      [channel setMessageHandler:nil];
-    }
-  }
-}
diff --git a/packages/google_sign_in/google_sign_in_ios/lib/google_sign_in_ios.dart b/packages/google_sign_in/google_sign_in_ios/lib/google_sign_in_ios.dart
index c1fe921a1c5b..b1368a1adb41 100644
--- a/packages/google_sign_in/google_sign_in_ios/lib/google_sign_in_ios.dart
+++ b/packages/google_sign_in/google_sign_in_ios/lib/google_sign_in_ios.dart
@@ -58,26 +58,18 @@ class GoogleSignInIOS extends GoogleSignInPlatform {
     AttemptLightweightAuthenticationParameters params,
   ) async {
     final SignInResult result = await _api.restorePreviousSignIn();
-
-    if (result.error?.type == GoogleSignInErrorCode.noAuthInKeychain) {
-      return null;
-    }
-
-    final SignInFailure? failure = result.error;
-    if (failure != null) {
-      throw GoogleSignInException(
-        code: _exceptionCodeForErrorPlatformErrorCode(failure.type),
-        description: failure.message,
-        details: failure.details,
-      );
+    switch (result) {
+      case SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain):
+        return null;
+      case SignInFailure(:final type, :final message, :final details):
+        throw GoogleSignInException(
+          code: _exceptionCodeForErrorPlatformErrorCode(type),
+          description: message,
+          details: details,
+        );
+      case SignInSuccess():
+        return _authenticationResultsFromSignInSuccess(result);
     }
-
-    // The native code must never return a null success and a null error.
-    // Switching the native implementation to Swift and using sealed classes
-    // in the Pigeon definition (see Android's messages.dart) will allow
-    // enforcing this via the type system instead of force unwrapping.
-    final SignInSuccess success = result.success!;
-    return _authenticationResultsFromSignInSuccess(success);
   }
 
   @override
@@ -86,31 +78,23 @@ class GoogleSignInIOS extends GoogleSignInPlatform {
   @override
   Future<AuthenticationResults> authenticate(AuthenticateParameters params) async {
     final SignInResult result = await _signIn(params.scopeHint, _nonce);
-
-    // This should never happen; the corresponding native error code is
-    // documented as being specific to restorePreviousSignIn.
-    if (result.error?.type == GoogleSignInErrorCode.noAuthInKeychain) {
-      throw const GoogleSignInException(
-        code: GoogleSignInExceptionCode.unknownError,
-        description: 'No auth reported during interactive sign in.',
-      );
+    switch (result) {
+      // This should never happen; the corresponding native error code is
+      // documented as being specific to restorePreviousSignIn.
+      case SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain):
+        throw const GoogleSignInException(
+          code: GoogleSignInExceptionCode.unknownError,
+          description: 'No auth reported during interactive sign in.',
+        );
+      case SignInFailure(:final type, :final message, :final details):
+        throw GoogleSignInException(
+          code: _exceptionCodeForErrorPlatformErrorCode(type),
+          description: message,
+          details: details,
+        );
+      case SignInSuccess():
+        return _authenticationResultsFromSignInSuccess(result);
     }
-
-    final SignInFailure? failure = result.error;
-    if (failure != null) {
-      throw GoogleSignInException(
-        code: _exceptionCodeForErrorPlatformErrorCode(failure.type),
-        description: failure.message,
-        details: failure.details,
-      );
-    }
-
-    // The native code must never return a null success and a null error.
-    // Switching the native implementation to Swift and using sealed classes
-    // in the Pigeon definition (see Android's messages.dart) will allow
-    // enforcing this via the type system instead of force unwrapping.
-    final SignInSuccess success = result.success!;
-    return _authenticationResultsFromSignInSuccess(success);
   }
 
   @override
@@ -154,30 +138,28 @@ class GoogleSignInIOS extends GoogleSignInPlatform {
   Future<({String? accessToken, String? serverAuthCode})> _getAuthorizationTokens(
     AuthorizationRequestDetails request,
   ) async {
-    String? userId = request.userId;
-
+    final String userId;
     // The Google Sign In SDK requires authentication before authorization, so
     // if the authentication isn't associated with an existing sign-in user
     // run the authentication flow first.
-    if (userId == null) {
-      SignInResult result = await _api.restorePreviousSignIn();
-      final SignInSuccess? success = result.success;
-      if (success == null) {
-        // There's no existing sign-in to use, so return the results of the
-        // combined authn+authz flow, if prompting is allowed.
-        if (request.promptIfUnauthorized) {
-          result = await _signIn(request.scopes, _nonce);
-          return _processAuthorizationResult(result);
-        } else {
+    if (request.userId case final requestedUserId?) {
+      userId = requestedUserId;
+    } else {
+      switch (await _api.restorePreviousSignIn()) {
+        case SignInSuccess(:final UserData user):
+          // Discard the authentication information, and extract the user ID to
+          // pass back to the authorization step so that it can re-associate
+          // with the currently signed in user on the native side.
+          userId = user.userId;
+        case SignInFailure():
+          // There's no existing sign-in to use, so return the results of the
+          // combined authn+authz flow, if prompting is allowed.
+          if (request.promptIfUnauthorized) {
+            return _processAuthorizationResult(await _signIn(request.scopes, _nonce));
+          }
           // No existing authentication, and no prompting allowed, so return
           // no tokens.
           return (accessToken: null, serverAuthCode: null);
-        }
-      } else {
-        // Discard the authentication information, and extract the user ID to
-        // pass back to the authorization step so that it can re-associate
-        // with the currently signed in user on the native side.
-        userId = success.user.userId;
       }
     }
 
@@ -186,13 +168,14 @@ class GoogleSignInIOS extends GoogleSignInPlatform {
         ? await _api.getRefreshedAuthorizationTokens(userId)
         : await _addScopes(request.scopes, userId);
     if (!useExistingAuthorization &&
-        result.error?.type == GoogleSignInErrorCode.scopesAlreadyGranted) {
+        result is SignInFailure &&
+        result.type == GoogleSignInErrorCode.scopesAlreadyGranted) {
       // The Google Sign In SDK returns an error when requesting scopes that are
       // already authorized, so in that case request updated tokens instead to
       // construct a valid token response.
       result = await _api.getRefreshedAuthorizationTokens(userId);
     }
-    if (result.error?.type == GoogleSignInErrorCode.noAuthInKeychain) {
+    if (result is SignInFailure && result.type == GoogleSignInErrorCode.noAuthInKeychain) {
       return (accessToken: null, serverAuthCode: null);
     }
 
@@ -200,7 +183,6 @@ class GoogleSignInIOS extends GoogleSignInPlatform {
     // requested scopes before returning it, as the list of requested scopes
     // may have changed since the last authorization.
     if (useExistingAuthorization) {
-      final SignInSuccess? success = result.success;
       // Don't validate the OpenID Connect scopes (see
       // https://developers.google.com/identity/protocols/oauth2/scopes#openid-connect
       // for details), as they should always be available, and the granted
@@ -208,7 +190,7 @@ class GoogleSignInIOS extends GoogleSignInPlatform {
       // For example, requesting 'email' can instead result in the grant
       // 'https://www.googleapis.com/auth/userinfo.email'.
       const openIdConnectScopes = <String>{'email', 'openid', 'profile'};
-      if (success != null) {
+      if (result case final SignInSuccess success) {
         if (request.scopes.any(
           (String scope) =>
               !openIdConnectScopes.contains(scope) && !success.grantedScopes.contains(scope),
@@ -224,21 +206,21 @@ class GoogleSignInIOS extends GoogleSignInPlatform {
   Future<({String? accessToken, String? serverAuthCode})> _processAuthorizationResult(
     SignInResult result,
   ) async {
-    final SignInFailure? failure = result.error;
-    if (failure != null) {
-      throw GoogleSignInException(
-        code: _exceptionCodeForErrorPlatformErrorCode(failure.type),
-        description: failure.message,
-        details: failure.details,
-      );
+    switch (result) {
+      case SignInFailure(:final type, :final message, :final details):
+        throw GoogleSignInException(
+          code: _exceptionCodeForErrorPlatformErrorCode(type),
+          description: message,
+          details: details,
+        );
+      case SignInSuccess():
+        return _authorizationTokenDataFromSignInSuccess(result);
     }
-
-    return _authorizationTokenDataFromSignInSuccess(result.success);
   }
 
   Future<SignInResult> _signIn(List<String> scopeHint, String? nonce) async {
     final SignInResult result = await _api.signIn(scopeHint, nonce);
-    _updateAuthCodeCache(result.success);
+    _updateAuthCodeCache(result is SignInSuccess ? result : null);
     return result;
   }
 
@@ -247,8 +229,8 @@ class GoogleSignInIOS extends GoogleSignInPlatform {
     // Don't clear the cache for GoogleSignInErrorCode.scopesAlreadyGranted
     // since that indicates that nothing has changed. Otherwise, update the
     // cache (with a new token on success, or clearing on failure).
-    if (result.error?.type != GoogleSignInErrorCode.scopesAlreadyGranted) {
-      _updateAuthCodeCache(result.success);
+    if (result is! SignInFailure || result.type != GoogleSignInErrorCode.scopesAlreadyGranted) {
+      _updateAuthCodeCache(result is SignInSuccess ? result : null);
     }
     return result;
   }
@@ -273,17 +255,16 @@ class GoogleSignInIOS extends GoogleSignInPlatform {
   }
 
   ({String? accessToken, String? serverAuthCode}) _authorizationTokenDataFromSignInSuccess(
-    SignInSuccess? result,
+    SignInSuccess result,
   ) {
     // Check for a relevant cached auth code to add if needed.
-    final String? cachedAuthCode =
-        result != null && result.user.userId == _cachedServerAuthCodeUserId
+    final String? cachedAuthCode = result.user.userId == _cachedServerAuthCodeUserId
         ? _cachedServerAuthCode
         : null;
 
     return (
-      accessToken: result?.accessToken,
-      serverAuthCode: result?.serverAuthCode ?? cachedAuthCode,
+      accessToken: result.accessToken,
+      serverAuthCode: result.serverAuthCode ?? cachedAuthCode,
     );
   }
 
diff --git a/packages/google_sign_in/google_sign_in_ios/lib/src/messages.g.dart b/packages/google_sign_in/google_sign_in_ios/lib/src/messages.g.dart
index c71cfdd6d04c..e8f450c747bb 100644
--- a/packages/google_sign_in/google_sign_in_ios/lib/src/messages.g.dart
+++ b/packages/google_sign_in/google_sign_in_ios/lib/src/messages.g.dart
@@ -247,56 +247,10 @@ class UserData {
 }
 
 /// The response from an auth call.
-class SignInResult {
-  SignInResult({this.success, this.error});
+sealed class SignInResult {}
 
-  /// The success result, if any.
-  ///
-  /// Exactly one of success and error will be non-nil.
-  SignInSuccess? success;
-
-  /// The error result, if any.
-  ///
-  /// Exactly one of success and error will be non-nil.
-  SignInFailure? error;
-
-  List<Object?> _toList() {
-    return <Object?>[success, error];
-  }
-
-  Object encode() {
-    return _toList();
-  }
-
-  static SignInResult decode(Object result) {
-    result as List<Object?>;
-    return SignInResult(success: result[0] as SignInSuccess?, error: result[1] as SignInFailure?);
-  }
-
-  @override
-  // ignore: avoid_equals_and_hash_code_on_mutable_classes
-  bool operator ==(Object other) {
-    if (other is! SignInResult || other.runtimeType != runtimeType) {
-      return false;
-    }
-    if (identical(this, other)) {
-      return true;
-    }
-    return _deepEquals(success, other.success) && _deepEquals(error, other.error);
-  }
-
-  @override
-  // ignore: avoid_equals_and_hash_code_on_mutable_classes
-  int get hashCode => _deepHash(<Object?>[runtimeType, ..._toList()]);
-
-  @override
-  String toString() {
-    return 'SignInResult(success: $success, error: $error)';
-  }
-}
-
-/// An sign in failure.
-class SignInFailure {
+/// A sign in failure.
+class SignInFailure extends SignInResult {
   SignInFailure({required this.type, this.message, this.details});
 
   /// The type of failure.
@@ -355,7 +309,7 @@ class SignInFailure {
 /// structure of the Google Sign In SDK, this has information corresponding to
 /// both authn and authz steps, even though incremental authorization is
 /// supported.
-class SignInSuccess {
+class SignInSuccess extends SignInResult {
   SignInSuccess({
     required this.user,
     required this.accessToken,
@@ -430,14 +384,11 @@ class _PigeonCodec extends StandardMessageCodec {
     } else if (value is UserData) {
       buffer.putUint8(131);
       writeValue(buffer, value.encode());
-    } else if (value is SignInResult) {
-      buffer.putUint8(132);
-      writeValue(buffer, value.encode());
     } else if (value is SignInFailure) {
-      buffer.putUint8(133);
+      buffer.putUint8(132);
       writeValue(buffer, value.encode());
     } else if (value is SignInSuccess) {
-      buffer.putUint8(134);
+      buffer.putUint8(133);
       writeValue(buffer, value.encode());
     } else {
       super.writeValue(buffer, value);
@@ -455,10 +406,8 @@ class _PigeonCodec extends StandardMessageCodec {
       case 131:
         return UserData.decode(readValue(buffer)!);
       case 132:
-        return SignInResult.decode(readValue(buffer)!);
-      case 133:
         return SignInFailure.decode(readValue(buffer)!);
-      case 134:
+      case 133:
         return SignInSuccess.decode(readValue(buffer)!);
       default:
         return super.readValueOfType(type, buffer);
diff --git a/packages/google_sign_in/google_sign_in_ios/pigeons/messages.dart b/packages/google_sign_in/google_sign_in_ios/pigeons/messages.dart
index 39770692c23b..f35708bf505c 100644
--- a/packages/google_sign_in/google_sign_in_ios/pigeons/messages.dart
+++ b/packages/google_sign_in/google_sign_in_ios/pigeons/messages.dart
@@ -7,13 +7,8 @@ import 'package:pigeon/pigeon.dart';
 @ConfigurePigeon(
   PigeonOptions(
     dartOut: 'lib/src/messages.g.dart',
-    objcHeaderOut:
-        'darwin/google_sign_in_ios/Sources/google_sign_in_ios_objc/include/google_sign_in_ios/messages.g.h',
-    objcSourceOut: 'darwin/google_sign_in_ios/Sources/google_sign_in_ios_objc/messages.g.m',
-    objcOptions: ObjcOptions(
-      prefix: 'FSI',
-      headerIncludePath: './include/google_sign_in_ios/messages.g.h',
-    ),
+    swiftOut: 'darwin/google_sign_in_ios/Sources/google_sign_in_ios/messages.g.swift',
+    swiftOptions: SwiftOptions(fileSpecificClassNameComponent: 'Messages'),
     copyrightHeader: 'pigeons/copyright.txt',
   ),
 )
@@ -76,22 +71,10 @@ enum GoogleSignInErrorCode {
 }
 
 /// The response from an auth call.
-// TODO(stuartmorgan): Switch to a sealed base class with two subclasses instead
-// of using composition when the plugin is migrated to Swift.
-class SignInResult {
-  /// The success result, if any.
-  ///
-  /// Exactly one of success and error will be non-nil.
-  SignInSuccess? success;
-
-  /// The error result, if any.
-  ///
-  /// Exactly one of success and error will be non-nil.
-  SignInFailure? error;
-}
+sealed class SignInResult {}
 
-/// An sign in failure.
-class SignInFailure {
+/// A sign in failure.
+class SignInFailure extends SignInResult {
   /// The type of failure.
   late GoogleSignInErrorCode type;
 
@@ -108,7 +91,7 @@ class SignInFailure {
 /// structure of the Google Sign In SDK, this has information corresponding to
 /// both authn and authz steps, even though incremental authorization is
 /// supported.
-class SignInSuccess {
+class SignInSuccess extends SignInResult {
   late UserData user;
 
   late String accessToken;
@@ -124,7 +107,6 @@ class SignInSuccess {
 @HostApi()
 abstract class GoogleSignInApi {
   /// Configures the sign in object with application-level parameters.
-  @ObjCSelector('configureWithParameters:')
   void configure(PlatformConfigurationParams params);
 
   /// Attempts to restore an existing sign-in, if any, with minimal user
@@ -134,17 +116,15 @@ abstract class GoogleSignInApi {
 
   /// Starts a sign in with user interaction.
   @async
-  @ObjCSelector('signInWithScopeHint:nonce:')
   SignInResult signIn(List<String> scopeHint, String? nonce);
 
   /// Requests the access token for the current sign in.
   @async
-  @ObjCSelector('refreshedAuthorizationTokensForUser:')
   SignInResult getRefreshedAuthorizationTokens(String userId);
 
   /// Requests authorization of the given additional scopes.
   @async
-  @ObjCSelector('addScopes:forUser:')
+  @SwiftFunction('addScopes(_:forUser:)')
   SignInResult addScopes(List<String> scopes, String userId);
 
   /// Signs out the current user.
diff --git a/packages/google_sign_in/google_sign_in_ios/pubspec.yaml b/packages/google_sign_in/google_sign_in_ios/pubspec.yaml
index 97e84fb3f124..eb9e3841055e 100644
--- a/packages/google_sign_in/google_sign_in_ios/pubspec.yaml
+++ b/packages/google_sign_in/google_sign_in_ios/pubspec.yaml
@@ -2,7 +2,7 @@ name: google_sign_in_ios
 description: iOS implementation of the google_sign_in plugin.
 repository: https://github.com/flutter/packages/tree/main/packages/google_sign_in/google_sign_in_ios
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+google_sign_in%22
-version: 6.3.5
+version: 6.3.6
 
 environment:
   sdk: ^3.11.0
diff --git a/packages/google_sign_in/google_sign_in_ios/test/google_sign_in_ios_test.dart b/packages/google_sign_in/google_sign_in_ios/test/google_sign_in_ios_test.dart
index 459d117d045e..0b81f97a0200 100644
--- a/packages/google_sign_in/google_sign_in_ios/test/google_sign_in_ios_test.dart
+++ b/packages/google_sign_in/google_sign_in_ios/test/google_sign_in_ios_test.dart
@@ -18,7 +18,7 @@ const GoogleSignInUserData _testUser = GoogleSignInUserData(
   displayName: 'John Doe',
 );
 
-@GenerateMocks(<Type>[GoogleSignInApi])
+@GenerateNiceMocks(<MockSpec<Object>>[MockSpec<GoogleSignInApi>()])
 void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
 
@@ -28,6 +28,7 @@ void main() {
   setUp(() {
     mockApi = MockGoogleSignInApi();
     googleSignIn = GoogleSignInIOS(api: mockApi);
+    provideDummy<SignInResult>(SignInFailure(type: GoogleSignInErrorCode.unknown));
   });
 
   test('registered instance', () {
@@ -71,18 +72,16 @@ void main() {
     test('passes success data to caller', () async {
       const idToken = 'idToken';
       when(mockApi.restorePreviousSignIn()).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: idToken,
-            ),
-            accessToken: '',
-            grantedScopes: <String>[],
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: idToken,
           ),
+          accessToken: '',
+          grantedScopes: <String>[],
         ),
       );
 
@@ -95,10 +94,9 @@ void main() {
     });
 
     test('returns null for missing auth', () async {
-      when(mockApi.restorePreviousSignIn()).thenAnswer(
-        (_) async =>
-            SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain)),
-      );
+      when(
+        mockApi.restorePreviousSignIn(),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain));
 
       final AuthenticationResults? result = await googleSignIn.attemptLightweightAuthentication(
         const AttemptLightweightAuthenticationParameters(),
@@ -108,9 +106,9 @@ void main() {
     });
 
     test('throws for other errors', () async {
-      when(mockApi.restorePreviousSignIn()).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.keychainError)),
-      );
+      when(
+        mockApi.restorePreviousSignIn(),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.keychainError));
 
       expect(
         googleSignIn.attemptLightweightAuthentication(
@@ -131,18 +129,16 @@ void main() {
     test('passes nonce if provided', () async {
       const nonce = 'nonce';
       when(mockApi.signIn(any, nonce)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: '',
-            ),
-            accessToken: '',
-            grantedScopes: <String>[],
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: '',
           ),
+          accessToken: '',
+          grantedScopes: <String>[],
         ),
       );
 
@@ -155,18 +151,16 @@ void main() {
     test('passes success data to caller', () async {
       const idToken = 'idToken';
       when(mockApi.signIn(any, null)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: idToken,
-            ),
-            accessToken: '',
-            grantedScopes: <String>[],
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: idToken,
           ),
+          accessToken: '',
+          grantedScopes: <String>[],
         ),
       );
 
@@ -179,10 +173,9 @@ void main() {
     });
 
     test('throws unknown for missing auth', () async {
-      when(mockApi.signIn(any, null)).thenAnswer(
-        (_) async =>
-            SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain)),
-      );
+      when(
+        mockApi.signIn(any, null),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain));
 
       expect(
         googleSignIn.authenticate(const AuthenticateParameters()),
@@ -203,9 +196,9 @@ void main() {
     });
 
     test('throws provider configuration error for keychain error', () async {
-      when(mockApi.signIn(any, null)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.keychainError)),
-      );
+      when(
+        mockApi.signIn(any, null),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.keychainError));
 
       expect(
         googleSignIn.authenticate(const AuthenticateParameters()),
@@ -220,9 +213,9 @@ void main() {
     });
 
     test('throws provider configuration error for EEM error', () async {
-      when(mockApi.signIn(any, null)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.eemError)),
-      );
+      when(
+        mockApi.signIn(any, null),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.eemError));
 
       expect(
         googleSignIn.authenticate(const AuthenticateParameters()),
@@ -237,9 +230,9 @@ void main() {
     });
 
     test('throws canceled from SDK', () async {
-      when(mockApi.signIn(any, null)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.canceled)),
-      );
+      when(
+        mockApi.signIn(any, null),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.canceled));
 
       expect(
         googleSignIn.authenticate(const AuthenticateParameters()),
@@ -254,9 +247,9 @@ void main() {
     });
 
     test('throws user mismatch from SDK', () async {
-      when(mockApi.signIn(any, null)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.userMismatch)),
-      );
+      when(
+        mockApi.signIn(any, null),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.userMismatch));
 
       expect(
         googleSignIn.authenticate(const AuthenticateParameters()),
@@ -271,9 +264,9 @@ void main() {
     });
 
     test('throws unknown from SDK', () async {
-      when(mockApi.signIn(any, null)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.unknown)),
-      );
+      when(
+        mockApi.signIn(any, null),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.unknown));
 
       expect(
         googleSignIn.authenticate(const AuthenticateParameters()),
@@ -301,18 +294,16 @@ void main() {
     test('passes expected values to addScopes if interaction is allowed', () async {
       const scopes = <String>['a', 'b'];
       when(mockApi.addScopes(any, _testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: '',
-            ),
-            accessToken: '',
-            grantedScopes: scopes,
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: '',
           ),
+          accessToken: '',
+          grantedScopes: scopes,
         ),
       );
 
@@ -336,18 +327,16 @@ void main() {
         'interaction is not allowed', () async {
       const scopes = <String>['a', 'b'];
       when(mockApi.getRefreshedAuthorizationTokens(_testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: '',
-            ),
-            accessToken: '',
-            grantedScopes: scopes,
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: '',
           ),
+          accessToken: '',
+          grantedScopes: scopes,
         ),
       );
 
@@ -367,18 +356,16 @@ void main() {
 
     test('attempts to restore previous sign in if no user is provided', () async {
       const scopes = <String>['a', 'b'];
-      final signInResult = SignInResult(
-        success: SignInSuccess(
-          user: UserData(
-            displayName: _testUser.displayName,
-            email: _testUser.email,
-            userId: _testUser.id,
-            photoUrl: _testUser.photoUrl,
-            idToken: '',
-          ),
-          accessToken: '',
-          grantedScopes: <String>[],
+      final signInResult = SignInSuccess(
+        user: UserData(
+          displayName: _testUser.displayName,
+          email: _testUser.email,
+          userId: _testUser.id,
+          photoUrl: _testUser.photoUrl,
+          idToken: '',
         ),
+        accessToken: '',
+        grantedScopes: <String>[],
       );
       when(mockApi.restorePreviousSignIn()).thenAnswer((_) async => signInResult);
       when(
@@ -404,10 +391,9 @@ void main() {
     });
 
     test('returns null if unauthenticated and interaction is not allowed', () async {
-      when(mockApi.restorePreviousSignIn()).thenAnswer(
-        (_) async =>
-            SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain)),
-      );
+      when(
+        mockApi.restorePreviousSignIn(),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain));
 
       final ClientAuthorizationTokenData? result = await googleSignIn
           .clientAuthorizationTokensForScopes(
@@ -432,23 +418,20 @@ void main() {
     test('attempts to authenticate if no user is provided or already signed in '
         'and interaction is allowed', () async {
       const scopes = <String>['a', 'b'];
-      when(mockApi.restorePreviousSignIn()).thenAnswer(
-        (_) async =>
-            SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain)),
-      );
+      when(
+        mockApi.restorePreviousSignIn(),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain));
       when(mockApi.signIn(scopes, null)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: '',
-            ),
-            accessToken: '',
-            grantedScopes: <String>[],
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: '',
           ),
+          accessToken: '',
+          grantedScopes: <String>[],
         ),
       );
 
@@ -474,18 +457,16 @@ void main() {
       const scopes = <String>['a', 'b'];
       const accessToken = 'token';
       when(mockApi.getRefreshedAuthorizationTokens(_testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: 'idToken',
-            ),
-            accessToken: accessToken,
-            grantedScopes: scopes,
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: 'idToken',
           ),
+          accessToken: accessToken,
+          grantedScopes: scopes,
         ),
       );
 
@@ -508,18 +489,16 @@ void main() {
       const scopes = <String>['a', 'b'];
       const accessToken = 'token';
       when(mockApi.addScopes(scopes, _testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: 'idToken',
-            ),
-            accessToken: accessToken,
-            grantedScopes: scopes,
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: 'idToken',
           ),
+          accessToken: accessToken,
+          grantedScopes: scopes,
         ),
       );
 
@@ -542,23 +521,20 @@ void main() {
         'requested scopes are already granted', () async {
       const scopes = <String>['a', 'b'];
       const accessToken = 'token';
-      when(mockApi.addScopes(scopes, _testUser.id)).thenAnswer(
-        (_) async =>
-            SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.scopesAlreadyGranted)),
-      );
+      when(
+        mockApi.addScopes(scopes, _testUser.id),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.scopesAlreadyGranted));
       when(mockApi.getRefreshedAuthorizationTokens(_testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: 'idToken',
-            ),
-            accessToken: accessToken,
-            grantedScopes: scopes,
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: 'idToken',
           ),
+          accessToken: accessToken,
+          grantedScopes: scopes,
         ),
       );
 
@@ -585,18 +561,16 @@ void main() {
       const grantedScopes = <String>['a'];
       const accessToken = 'token';
       when(mockApi.getRefreshedAuthorizationTokens(_testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: 'idToken',
-            ),
-            accessToken: accessToken,
-            grantedScopes: grantedScopes,
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: 'idToken',
           ),
+          accessToken: accessToken,
+          grantedScopes: grantedScopes,
         ),
       );
 
@@ -616,10 +590,9 @@ void main() {
     });
 
     test('returns null when unauthorized', () async {
-      when(mockApi.restorePreviousSignIn()).thenAnswer(
-        (_) async =>
-            SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain)),
-      );
+      when(
+        mockApi.restorePreviousSignIn(),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain));
 
       expect(
         await googleSignIn.clientAuthorizationTokensForScopes(
@@ -630,9 +603,9 @@ void main() {
     });
 
     test('thows canceled from SDK', () async {
-      when(mockApi.addScopes(any, any)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.canceled)),
-      );
+      when(
+        mockApi.addScopes(any, any),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.canceled));
 
       expect(
         googleSignIn.clientAuthorizationTokensForScopes(
@@ -656,9 +629,9 @@ void main() {
     });
 
     test('throws unknown from SDK', () async {
-      when(mockApi.addScopes(any, any)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.unknown)),
-      );
+      when(
+        mockApi.addScopes(any, any),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.unknown));
 
       expect(
         googleSignIn.clientAuthorizationTokensForScopes(
@@ -682,9 +655,9 @@ void main() {
     });
 
     test('throws user mismatch from SDK', () async {
-      when(mockApi.addScopes(any, any)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.userMismatch)),
-      );
+      when(
+        mockApi.addScopes(any, any),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.userMismatch));
 
       expect(
         googleSignIn.clientAuthorizationTokensForScopes(
@@ -721,18 +694,16 @@ void main() {
     test('passes expected values to addScopes if interaction is allowed', () async {
       const scopes = <String>['a', 'b'];
       when(mockApi.addScopes(any, _testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: '',
-            ),
-            accessToken: '',
-            grantedScopes: scopes,
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: '',
           ),
+          accessToken: '',
+          grantedScopes: scopes,
         ),
       );
 
@@ -756,18 +727,16 @@ void main() {
         'interaction is not allowed', () async {
       const scopes = <String>['a', 'b'];
       when(mockApi.getRefreshedAuthorizationTokens(_testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: '',
-            ),
-            accessToken: '',
-            grantedScopes: scopes,
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: '',
           ),
+          accessToken: '',
+          grantedScopes: scopes,
         ),
       );
 
@@ -787,18 +756,16 @@ void main() {
 
     test('attempts to restore previous sign in if no user is provided', () async {
       const scopes = <String>['a', 'b'];
-      final signInResult = SignInResult(
-        success: SignInSuccess(
-          user: UserData(
-            displayName: _testUser.displayName,
-            email: _testUser.email,
-            userId: _testUser.id,
-            photoUrl: _testUser.photoUrl,
-            idToken: '',
-          ),
-          accessToken: '',
-          grantedScopes: <String>[],
+      final signInResult = SignInSuccess(
+        user: UserData(
+          displayName: _testUser.displayName,
+          email: _testUser.email,
+          userId: _testUser.id,
+          photoUrl: _testUser.photoUrl,
+          idToken: '',
         ),
+        accessToken: '',
+        grantedScopes: <String>[],
       );
       when(mockApi.restorePreviousSignIn()).thenAnswer((_) async => signInResult);
       when(
@@ -824,10 +791,9 @@ void main() {
     });
 
     test('returns null if unauthenticated and interaction is not allowed', () async {
-      when(mockApi.restorePreviousSignIn()).thenAnswer(
-        (_) async =>
-            SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain)),
-      );
+      when(
+        mockApi.restorePreviousSignIn(),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain));
 
       final ServerAuthorizationTokenData? result = await googleSignIn
           .serverAuthorizationTokensForScopes(
@@ -852,23 +818,20 @@ void main() {
     test('attempts to authenticate if no user is provided or already signed in '
         'and interaction is allowed', () async {
       const scopes = <String>['a', 'b'];
-      when(mockApi.restorePreviousSignIn()).thenAnswer(
-        (_) async =>
-            SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain)),
-      );
+      when(
+        mockApi.restorePreviousSignIn(),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain));
       when(mockApi.signIn(scopes, null)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: '',
-            ),
-            accessToken: '',
-            grantedScopes: <String>[],
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: '',
           ),
+          accessToken: '',
+          grantedScopes: <String>[],
         ),
       );
 
@@ -902,23 +865,19 @@ void main() {
       const accessToken = 'accessToken';
       const serverAuthCode = 'authCode';
       when(mockApi.signIn(scopes, null)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: accessToken,
-            serverAuthCode: serverAuthCode,
-            grantedScopes: <String>[],
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: accessToken,
+          serverAuthCode: serverAuthCode,
+          grantedScopes: <String>[],
         ),
       );
       when(mockApi.getRefreshedAuthorizationTokens(_testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: accessToken,
-            // serverAuthCode will always be null for getRefreshedAuthorizationTokens.
-            grantedScopes: scopes,
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: accessToken,
+          // serverAuthCode will always be null for getRefreshedAuthorizationTokens.
+          grantedScopes: scopes,
         ),
       );
 
@@ -957,23 +916,19 @@ void main() {
         idToken: '',
       );
       when(mockApi.signIn(scopes, null)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: previousUser,
-            accessToken: accessToken,
-            serverAuthCode: serverAuthCode,
-            grantedScopes: <String>[],
-          ),
+        (_) async => SignInSuccess(
+          user: previousUser,
+          accessToken: accessToken,
+          serverAuthCode: serverAuthCode,
+          grantedScopes: <String>[],
         ),
       );
       when(mockApi.getRefreshedAuthorizationTokens(newUser.userId)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: newUser,
-            accessToken: accessToken,
-            // serverAuthCode will always be null for getRefreshedAuthorizationTokens.
-            grantedScopes: scopes,
-          ),
+        (_) async => SignInSuccess(
+          user: newUser,
+          accessToken: accessToken,
+          // serverAuthCode will always be null for getRefreshedAuthorizationTokens.
+          grantedScopes: scopes,
         ),
       );
 
@@ -1005,23 +960,19 @@ void main() {
         idToken: '',
       );
       when(mockApi.signIn(scopes, null)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: accessToken,
-            serverAuthCode: serverAuthCode,
-            grantedScopes: <String>[],
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: accessToken,
+          serverAuthCode: serverAuthCode,
+          grantedScopes: <String>[],
         ),
       );
       when(mockApi.getRefreshedAuthorizationTokens(userData.userId)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: accessToken,
-            // serverAuthCode will always be null for getRefreshedAuthorizationTokens.
-            grantedScopes: scopes,
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: accessToken,
+          // serverAuthCode will always be null for getRefreshedAuthorizationTokens.
+          grantedScopes: scopes,
         ),
       );
 
@@ -1054,23 +1005,19 @@ void main() {
         idToken: '',
       );
       when(mockApi.signIn(scopes, null)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: accessToken,
-            serverAuthCode: serverAuthCode,
-            grantedScopes: <String>[],
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: accessToken,
+          serverAuthCode: serverAuthCode,
+          grantedScopes: <String>[],
         ),
       );
       when(mockApi.getRefreshedAuthorizationTokens(userData.userId)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: accessToken,
-            // serverAuthCode will always be null for getRefreshedAuthorizationTokens.
-            grantedScopes: scopes,
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: accessToken,
+          // serverAuthCode will always be null for getRefreshedAuthorizationTokens.
+          grantedScopes: scopes,
         ),
       );
 
@@ -1095,19 +1042,17 @@ void main() {
       const scopes = <String>['a', 'b'];
       const serverAuthCode = 'authCode';
       when(mockApi.addScopes(scopes, _testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: UserData(
-              displayName: _testUser.displayName,
-              email: _testUser.email,
-              userId: _testUser.id,
-              photoUrl: _testUser.photoUrl,
-              idToken: 'idToken',
-            ),
-            accessToken: 'token',
-            serverAuthCode: serverAuthCode,
-            grantedScopes: scopes,
+        (_) async => SignInSuccess(
+          user: UserData(
+            displayName: _testUser.displayName,
+            email: _testUser.email,
+            userId: _testUser.id,
+            photoUrl: _testUser.photoUrl,
+            idToken: 'idToken',
           ),
+          accessToken: 'token',
+          serverAuthCode: serverAuthCode,
+          grantedScopes: scopes,
         ),
       );
 
@@ -1137,23 +1082,19 @@ void main() {
       );
       const serverAuthCode = 'authCode';
       when(mockApi.signIn(<String>[], null)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: 'token',
-            serverAuthCode: 'no-scope-auth-code',
-            grantedScopes: <String>[],
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: 'token',
+          serverAuthCode: 'no-scope-auth-code',
+          grantedScopes: <String>[],
         ),
       );
       when(mockApi.addScopes(scopes, _testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: 'token',
-            serverAuthCode: serverAuthCode,
-            grantedScopes: scopes,
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: 'token',
+          serverAuthCode: serverAuthCode,
+          grantedScopes: scopes,
         ),
       );
 
@@ -1185,27 +1126,22 @@ void main() {
         idToken: 'idToken',
       );
       when(mockApi.signIn(scopes, null)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: 'token',
-            serverAuthCode: serverAuthCode,
-            grantedScopes: scopes,
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: 'token',
+          serverAuthCode: serverAuthCode,
+          grantedScopes: scopes,
         ),
       );
-      when(mockApi.addScopes(scopes, _testUser.id)).thenAnswer(
-        (_) async =>
-            SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.scopesAlreadyGranted)),
-      );
+      when(
+        mockApi.addScopes(scopes, _testUser.id),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.scopesAlreadyGranted));
       when(mockApi.getRefreshedAuthorizationTokens(_testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: 'token',
-            // serverAuthCode will always be null for getRefreshedAuthorizationTokens.
-            grantedScopes: scopes,
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: 'token',
+          // serverAuthCode will always be null for getRefreshedAuthorizationTokens.
+          grantedScopes: scopes,
         ),
       );
 
@@ -1240,23 +1176,19 @@ void main() {
         idToken: 'idToken',
       );
       when(mockApi.signIn(<String>[], null)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: 'token',
-            serverAuthCode: 'no-scope-auth-code',
-            grantedScopes: <String>[],
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: 'token',
+          serverAuthCode: 'no-scope-auth-code',
+          grantedScopes: <String>[],
         ),
       );
       when(mockApi.getRefreshedAuthorizationTokens(_testUser.id)).thenAnswer(
-        (_) async => SignInResult(
-          success: SignInSuccess(
-            user: userData,
-            accessToken: accessToken,
-            serverAuthCode: 'wrong-scope-auth-code',
-            grantedScopes: grantedScopes,
-          ),
+        (_) async => SignInSuccess(
+          user: userData,
+          accessToken: accessToken,
+          serverAuthCode: 'wrong-scope-auth-code',
+          grantedScopes: grantedScopes,
         ),
       );
 
@@ -1277,10 +1209,9 @@ void main() {
     });
 
     test('returns null when unauthorized', () async {
-      when(mockApi.restorePreviousSignIn()).thenAnswer(
-        (_) async =>
-            SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain)),
-      );
+      when(
+        mockApi.restorePreviousSignIn(),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.noAuthInKeychain));
 
       expect(
         await googleSignIn.serverAuthorizationTokensForScopes(
@@ -1291,9 +1222,9 @@ void main() {
     });
 
     test('thows canceled from SDK', () async {
-      when(mockApi.addScopes(any, any)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.canceled)),
-      );
+      when(
+        mockApi.addScopes(any, any),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.canceled));
 
       expect(
         googleSignIn.serverAuthorizationTokensForScopes(
@@ -1317,9 +1248,9 @@ void main() {
     });
 
     test('throws unknown from SDK', () async {
-      when(mockApi.addScopes(any, any)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.unknown)),
-      );
+      when(
+        mockApi.addScopes(any, any),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.unknown));
 
       expect(
         googleSignIn.serverAuthorizationTokensForScopes(
@@ -1343,9 +1274,9 @@ void main() {
     });
 
     test('throws user mismatch from SDK', () async {
-      when(mockApi.addScopes(any, any)).thenAnswer(
-        (_) async => SignInResult(error: SignInFailure(type: GoogleSignInErrorCode.userMismatch)),
-      );
+      when(
+        mockApi.addScopes(any, any),
+      ).thenAnswer((_) async => SignInFailure(type: GoogleSignInErrorCode.userMismatch));
 
       expect(
         googleSignIn.serverAuthorizationTokensForScopes(
diff --git a/packages/google_sign_in/google_sign_in_ios/test/google_sign_in_ios_test.mocks.dart b/packages/google_sign_in/google_sign_in_ios/test/google_sign_in_ios_test.mocks.dart
index 31a501c14361..ee104e7e3531 100644
--- a/packages/google_sign_in/google_sign_in_ios/test/google_sign_in_ios_test.mocks.dart
+++ b/packages/google_sign_in/google_sign_in_ios/test/google_sign_in_ios_test.mocks.dart
@@ -22,19 +22,12 @@ import 'package:mockito/src/dummies.dart' as _i3;
 // ignore_for_file: unnecessary_parenthesis
 // ignore_for_file: camel_case_types
 // ignore_for_file: subtype_of_sealed_class
-
-class _FakeSignInResult_0 extends _i1.SmartFake implements _i2.SignInResult {
-  _FakeSignInResult_0(Object parent, Invocation parentInvocation) : super(parent, parentInvocation);
-}
+// ignore_for_file: invalid_use_of_internal_member
 
 /// A class which mocks [GoogleSignInApi].
 ///
 /// See the documentation for Mockito's code generation for more information.
 class MockGoogleSignInApi extends _i1.Mock implements _i2.GoogleSignInApi {
-  MockGoogleSignInApi() {
-    _i1.throwOnMissingStub(this);
-  }
-
   @override
   String get pigeonVar_messageChannelSuffix =>
       (super.noSuchMethod(
@@ -43,6 +36,10 @@ class MockGoogleSignInApi extends _i1.Mock implements _i2.GoogleSignInApi {
               this,
               Invocation.getter(#pigeonVar_messageChannelSuffix),
             ),
+            returnValueForMissingStub: _i3.dummyValue<String>(
+              this,
+              Invocation.getter(#pigeonVar_messageChannelSuffix),
+            ),
           )
           as String);
 
@@ -60,7 +57,10 @@ class MockGoogleSignInApi extends _i1.Mock implements _i2.GoogleSignInApi {
       (super.noSuchMethod(
             Invocation.method(#restorePreviousSignIn, []),
             returnValue: _i4.Future<_i2.SignInResult>.value(
-              _FakeSignInResult_0(this, Invocation.method(#restorePreviousSignIn, [])),
+              _i3.dummyValue<_i2.SignInResult>(this, Invocation.method(#restorePreviousSignIn, [])),
+            ),
+            returnValueForMissingStub: _i4.Future<_i2.SignInResult>.value(
+              _i3.dummyValue<_i2.SignInResult>(this, Invocation.method(#restorePreviousSignIn, [])),
             ),
           )
           as _i4.Future<_i2.SignInResult>);
@@ -70,7 +70,16 @@ class MockGoogleSignInApi extends _i1.Mock implements _i2.GoogleSignInApi {
       (super.noSuchMethod(
             Invocation.method(#signIn, [scopeHint, nonce]),
             returnValue: _i4.Future<_i2.SignInResult>.value(
-              _FakeSignInResult_0(this, Invocation.method(#signIn, [scopeHint, nonce])),
+              _i3.dummyValue<_i2.SignInResult>(
+                this,
+                Invocation.method(#signIn, [scopeHint, nonce]),
+              ),
+            ),
+            returnValueForMissingStub: _i4.Future<_i2.SignInResult>.value(
+              _i3.dummyValue<_i2.SignInResult>(
+                this,
+                Invocation.method(#signIn, [scopeHint, nonce]),
+              ),
             ),
           )
           as _i4.Future<_i2.SignInResult>);
@@ -80,7 +89,13 @@ class MockGoogleSignInApi extends _i1.Mock implements _i2.GoogleSignInApi {
       (super.noSuchMethod(
             Invocation.method(#getRefreshedAuthorizationTokens, [userId]),
             returnValue: _i4.Future<_i2.SignInResult>.value(
-              _FakeSignInResult_0(
+              _i3.dummyValue<_i2.SignInResult>(
+                this,
+                Invocation.method(#getRefreshedAuthorizationTokens, [userId]),
+              ),
+            ),
+            returnValueForMissingStub: _i4.Future<_i2.SignInResult>.value(
+              _i3.dummyValue<_i2.SignInResult>(
                 this,
                 Invocation.method(#getRefreshedAuthorizationTokens, [userId]),
               ),
@@ -93,7 +108,16 @@ class MockGoogleSignInApi extends _i1.Mock implements _i2.GoogleSignInApi {
       (super.noSuchMethod(
             Invocation.method(#addScopes, [scopes, userId]),
             returnValue: _i4.Future<_i2.SignInResult>.value(
-              _FakeSignInResult_0(this, Invocation.method(#addScopes, [scopes, userId])),
+              _i3.dummyValue<_i2.SignInResult>(
+                this,
+                Invocation.method(#addScopes, [scopes, userId]),
+              ),
+            ),
+            returnValueForMissingStub: _i4.Future<_i2.SignInResult>.value(
+              _i3.dummyValue<_i2.SignInResult>(
+                this,
+                Invocation.method(#addScopes, [scopes, userId]),
+              ),
             ),
           )
           as _i4.Future<_i2.SignInResult>);