login_screen.dart

import 'package:apple_sign_in/apple_sign_in.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';

class LoginScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: AppleSignIn.isAvailable(),
      builder: (context, snapshot) {
        if (snapshot.data == true) {
          return AppleSignInButton(
            onPressed: () async {
              FirebaseUser user = await AuthService().signInWithApple();
              if (user != null) {
                Navigator.pushReplacementNamed(context, '/home');
              }
            },
          );
        } else {
          return Container();
        }
      },
    );
  }
}