Apple Sign in / sign up with Flutter

Implementing Apple Sign-In in a Flutter app involves a few steps. Apple Sign-In is a secure way for users to sign in to your app using their Apple ID. Here’s a step-by-step guide to integrating Apple Sign-In into your Flutter app:

1. Set Up Your Apple Developer Account:

• If you haven’t already, create an Apple Developer account at Apple Developer.
• Create an App ID for your Flutter app in the Apple Developer portal.

2 Enable Sign-In with Apple:

• In the Apple Developer portal, navigate to your App ID, and under “Capabilities,” enable “Sign In with Apple.”

3 Configure App in Firebase (Optional):

• If you’re using Firebase in your Flutter app, you can configure Apple Sign-In in the Firebase Console. This step is optional but can simplify the authentication process.
• and enable apple signin provider

4 Add Dependencies:

• Open your Flutter project’s pubspec.yaml file and add the following dependencies:

  sign_in_with_apple: ^5.0.0
  crypto: ^3.0.3

import 'dart:convert';
import 'dart:math';

import 'package:crypto/crypto.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:sign_in_with_apple/sign_in_with_apple.dart';

/// Generates a cryptographically secure random nonce, to be included in a
/// credential request.
String generateNonce([int length = 32]) {
  final charset =
      '0123456789ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz-._';
  final random = Random.secure();
  return List.generate(length, (_) => charset[random.nextInt(charset.length)])
      .join();
}

/// Returns the sha256 hash of [input] in hex notation.
String sha256ofString(String input) {
  final bytes = utf8.encode(input);
  final digest = sha256.convert(bytes);
  return digest.toString();
}

Future<UserCredential> signInWithApple() async {
  // To prevent replay attacks with the credential returned from Apple, we
  // include a nonce in the credential request. When signing in with
  // Firebase, the nonce in the id token returned by Apple, is expected to
  // match the sha256 hash of `rawNonce`.
  final rawNonce = generateNonce();
  final nonce = sha256ofString(rawNonce);

  // Request credential for the currently signed in Apple account.
  final appleCredential = await SignInWithApple.getAppleIDCredential(
    scopes: [
      AppleIDAuthorizationScopes.email,
      AppleIDAuthorizationScopes.fullName,
    ],
    nonce: nonce,
  );

  // Create an `OAuthCredential` from the credential returned by Apple.
  final oauthCredential = OAuthProvider("apple.com").credential(
    idToken: appleCredential.identityToken,
    rawNonce: rawNonce,
  );

  // Sign in the user with Firebase. If the nonce we generated earlier does
  // not match the nonce in `appleCredential.identityToken`, sign in will fail.
  return await FirebaseAuth.instance.signInWithCredential(oauthCredential);
}

than call this func to the apple signin Button

ElevatedButton(
  onPressed: signInWithApple,
  child: Text("Sign in with Apple"),
),