Flutter iOS Facebook Limited Login Bad Signature

Question

Package version used:

flutter_facebook_auth: ^7.0.0
firebase_core: ^2.24.2
firebase_auth: ^4.15.2
FBSDKLoginKit (17.0.2) //pod

I have tested recently with our app and can't login with Facebook and upon debugging, I've seen this error

Unhandled Exception: [firebase_auth/invalid-credential] {"code":190,"message":"Bad signature"}

Login attempt code:

Future<dynamic> signInWithFacebook() async {
  // try {
    final LoginResult loginResult = await _facebookAuth.login();

    if (loginResult.accessToken == null) {
      _hasError = true;
      _loginErrorMsg = 'Login cancelled.';
      notifyListeners();
      return null;
    }

    // Create a credential from the access token
    final OAuthCredential facebookAuthCredential =
        FacebookAuthProvider.credential(loginResult.accessToken!.tokenString);

    UserCredential userCredential = await FirebaseAuth.instance
        .signInWithCredential(facebookAuthCredential);
}

The result of loginResult is LoginStatus.success.

Is someone experiencing the same issue? What are the steps have you done to resolve?

Answer 1

Thanks for the inputs, I'm able to solve my issue by doing the following.

In info.plist, add this

<key>NSUserTrackingUsageDescription</key>
<string>This identifier will be used to deliver personalized ads to you.</string>

Please take note that you have to update the privacy in App Store Connect.

For my Login Button

void facebookSignIn(BuildContext context) async {
  final authProvider = AuthServiceProvider();

  //since we only have the problem with iOS
  if (Platform.isIOS) {
    TrackingStatus status =
        await AppTrackingTransparency.trackingAuthorizationStatus;

    if (status == TrackingStatus.notDetermined) {
      status = await AppTrackingTransparency.requestTrackingAuthorization();
    } else {
      if (status != TrackingStatus.authorized) {
        await openAppSettings();
      }
    }

    if (status != TrackingStatus.authorized) {
      Util.showSnackBar(
        context,
        'Login cancelled, to continue please allow this app to track your activity.',
      );
      return;
    }
  }

  WidgetsFlutterBinding.ensureInitialized().addPostFrameCallback(
    (_) async {

      await authProvider.signInWithFacebook().then(
        (value) async {
          //handle the result here
        },
      );
    },
  );
}

and in my auth.dart

Future<dynamic> signInWithFacebook() async {
  try {
    final LoginResult loginResult = await _facebookAuth.login(
      loginTracking: LoginTracking.enabled,
    );

    if (loginResult.accessToken == null) {
      _hasError = true;
      _loginErrorMsg = 'Login cancelled.';
      notifyListeners();
      return null;
    }

    // Create a credential from the access token
    final OAuthCredential facebookAuthCredential =
        FacebookAuthProvider.credential(loginResult.accessToken!.tokenString);

    UserCredential userCredential = await FirebaseAuth.instance
        .signInWithCredential(facebookAuthCredential);

    return userCredential;
  } on FirebaseAuthException catch (e) {
    //FirebaseAuthException error handling
    return null;
  } on Exception catch (e) {
    //error handling
    notifyListeners();
    return null;
  }
}