Flutter & Firebase - Apple Sign In not working - firebase

Question

I am trying to set up with apple sign in with the following code. When tapping the button nothing happens.
I get the following error:
Tried calling: authorizationCode
flutter: NoSuchMethodError: The getter 'authorizationCode' was called on null.
Receiver: null
How would I fix this?
Future<bool> get appleSignInAvailable => AppleSignIn.isAvailable();
Future<User> appleSignIn() async {
try {
final AuthorizationResult appleResult =
await AppleSignIn.performRequests([
AppleIdRequest(requestedScopes: [Scope.email, Scope.fullName])
]);
if (appleResult.error != null) {
// handle errors from Apple
}
final AuthCredential credential =
OAuthProvider('apple.com').credential(
accessToken:
String.fromCharCodes(appleResult.credential.authorizationCode),
idToken: String.fromCharCodes(appleResult.credential.identityToken),
);
UserCredential result =
await Global.fbAuth.signInWithCredential(credential);
User user = result.user;
updateUserData(user);
return user;
} catch (error) {
print(error);
return null;
}
}

Answer 1

If you are using iOS 14 simulator, this may be due to the issue reported here. The workaround would be to use a real device for debugging or use the iOS 13 simulator
Also, see this thread for reference

Answer 2

I have faced same kind of issue in one of my projects.You have to add your sha key in firebase and facebook to resolve the issue.
Also you can try the below code,
import 'package:apple_sign_in/apple_sign_in.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/services.dart';
class AuthService {
final _firebaseAuth = FirebaseAuth.instance;
Future<User> signInWithApple({List<Scope> scopes = const []}) async {
// 1. perform the sign-in request
final result = await AppleSignIn.performRequests(
[AppleIdRequest(requestedScopes: scopes)]);
// 2. check the result
switch (result.status) {
case AuthorizationStatus.authorized:
final appleIdCredential = result.credential;
final oAuthProvider = OAuthProvider('apple.com');
final credential = oAuthProvider.credential(
idToken: String.fromCharCodes(appleIdCredential.identityToken),
accessToken:
String.fromCharCodes(appleIdCredential.authorizationCode),
);
final authResult = await _firebaseAuth.signInWithCredential(credential);
final firebaseUser = authResult.user;
if (scopes.contains(Scope.fullName)) {
final displayName =
'${appleIdCredential.fullName.givenName} ${appleIdCredential.fullName.familyName}';
await firebaseUser.updateProfile(displayName: displayName);
}
return firebaseUser;
case AuthorizationStatus.error:
throw PlatformException(
code: 'ERROR_AUTHORIZATION_DENIED',
message: result.error.toString(),
);
case AuthorizationStatus.cancelled:
throw PlatformException(
code: 'ERROR_ABORTED_BY_USER',
message: 'Sign in aborted by user',
);
default:
throw UnimplementedError();
}
}
}