Complete Guide to Third-Party Authentication in Flutter with Parse on Back4App

43min
Introduction
Integrating third-party authentication methods like Facebook, Google, and Apple into your Flutter app can significantly enhance user experience by providing flexible and convenient login options. Parse Server, powered by Back4App, offers built-in support for these authentication providers. In this tutorial, you will learn how to implement third-party authentication in your Flutter app using the Parse SDK on Back4App.
By the end of this tutorial, you will have a Flutter app with fully functional signup and login features that include:
Standard email/password authentication using Parse.
Third-party authentication methods:
Facebook
Google
Apple
Prerequisites
To follow along with this tutorial, you'll need the following:
A Back4App account. Sign up for a free account at Back4App.
A Flutter development environment installed on your machine. Follow this guide if you need help setting up Flutter.
Basic knowledge of Flutter and Dart. If you're new, check out Flutter's introduction.
Developer accounts for Facebook, Google, and Apple (required for setting up third-party login methods).
An IDE or text editor such as Visual Studio Code or Android Studio.
Step 1 – Setting Up Your Back4App Backend
1.1. Create a Back4App Project
Log in to your Back4App dashboard.
Click on "Create new App".
Enter a name for your application, e.g., "AuthDemo", and click "Create".
Once the project is created, navigate to App Settings > Security & Keys.
Note down your Application ID and Client Key. You'll need these values to initialize Parse in your Flutter app.
1.2. Enable Authentication Providers
In your Back4App dashboard, navigate to Server Settings > Authentication.
Enable the authentication methods you intend to use:
Facebook
Google
Apple
For each provider, you will need to input specific credentials (App IDs, Client IDs, Secrets, etc.), which will be set up in the upcoming steps.
Step 2 – Installing and Setting Up Parse SDK in Flutter
2.1. Create a New Flutter Project
Open your terminal and create a new Flutter project:
Bash
flutter create auth_demo
cd auth_demo
flutter create auth_demo
cd auth_demo
﻿
2.2. Add Dependencies
Open pubspec.yaml and add the following dependencies for Parse and third-party sign-in options:
YAML
dependencies:
  flutter:
    sdk: flutter
  parse_server_sdk_flutter: ^4.0.1
  flutter_facebook_auth: ^5.0.5
  google_sign_in: ^5.4.0
  sign_in_with_apple: ^3.3.0
dependencies:
  flutter:
    sdk: flutter
  parse_server_sdk_flutter: ^4.0.1
  flutter_facebook_auth: ^5.0.5
  google_sign_in: ^5.4.0
  sign_in_with_apple: ^3.3.0
﻿
Run flutter pub get to install the dependencies.
2.3. Initialize Parse in main.dart
In the lib/main.dart file, import the Parse SDK and initialize it in the main function:
Dart
import 'package:flutter/material.dart';
import 'package:parse_server_sdk_flutter/parse_server_sdk.dart';
import 'screens/auth_screen.dart'; // You'll create this file later

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  const keyApplicationId = 'YOUR_APP_ID';
  const keyClientKey = 'YOUR_CLIENT_KEY';
  const keyParseServerUrl = 'https://parseapi.back4app.com';

  await Parse().initialize(
    keyApplicationId,
    keyParseServerUrl,
    clientKey: keyClientKey,
    autoSendSessionId: true,
    debug: true,
  );

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Parse Auth Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: AuthScreen(),
    );
  }
}
import 'package:flutter/material.dart';
import 'package:parse_server_sdk_flutter/parse_server_sdk.dart';
import 'screens/auth_screen.dart'; // You'll create this file later

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  const keyApplicationId = 'YOUR_APP_ID';
  const keyClientKey = 'YOUR_CLIENT_KEY';
  const keyParseServerUrl = 'https://parseapi.back4app.com';

  await Parse().initialize(
    keyApplicationId,
    keyParseServerUrl,
    clientKey: keyClientKey,
    autoSendSessionId: true,
    debug: true,
  );

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Parse Auth Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: AuthScreen(),
    );
  }
}
﻿
Replace 'YOUR_APP_ID' and 'YOUR_CLIENT_KEY' with your actual Back4App credentials from Step 1.
Step 3 – Implementing Standard Authentication
3.1. Create the Authentication Service
Create a new directory called services under lib and add a file named auth_service.dart. This service will handle user registration and login using Parse.
Dart
// lib/services/auth_service.dart
import 'package:parse_server_sdk_flutter/parse_server_sdk.dart';

class AuthService {
  Future<ParseUser?> signUp(String username, String password, String email) async {
    var user = ParseUser(username, password, email);

    var response = await user.signUp();

    if (response.success) {
      return user;
    } else {
      return null;
    }
  }

  Future<ParseUser?> login(String username, String password) async {
    var user = ParseUser(username, password, null);
    var response = await user.login();

    if (response.success) {
      return user;
    } else {
      return null;
    }
  }

  Future<void> logout() async {
    var user = await ParseUser.currentUser() as ParseUser?;
    await user?.logout();
  }
}
// lib/services/auth_service.dart
import 'package:parse_server_sdk_flutter/parse_server_sdk.dart';

class AuthService {
  Future<ParseUser?> signUp(String username, String password, String email) async {
    var user = ParseUser(username, password, email);

    var response = await user.signUp();

    if (response.success) {
      return user;
    } else {
      return null;
    }
  }

  Future<ParseUser?> login(String username, String password) async {
    var user = ParseUser(username, password, null);
    var response = await user.login();

    if (response.success) {
      return user;
    } else {
      return null;
    }
  }

  Future<void> logout() async {
    var user = await ParseUser.currentUser() as ParseUser?;
    await user?.logout();
  }
}
﻿
3.2. Create the Authentication Screen
Create a new directory called screens under lib and add a file named auth_screen.dart. This screen will provide the UI for standard authentication.
Dart
// lib/screens/auth_screen.dart
import 'package:flutter/material.dart';
import '../services/auth_service.dart';

class AuthScreen extends StatefulWidget {
  @override
  _AuthScreenState createState() => _AuthScreenState();
}

class _AuthScreenState extends State<AuthScreen> {
  final TextEditingController _usernameController = TextEditingController();
  final TextEditingController _passwordController = TextEditingController();
  final TextEditingController _emailController = TextEditingController();
  final AuthService _authService = AuthService();

  void _signUp() async {
    var user = await _authService.signUp(
      _usernameController.text.trim(),
      _passwordController.text.trim(),
      _emailController.text.trim(),
    );
    if (user != null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('User created successfully!')));
    } else {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Sign up failed.')));
    }
  }

  void _login() async {
    var user = await _authService.login(
      _usernameController.text.trim(),
      _passwordController.text.trim(),
    );
    if (user != null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Login successful!')));
    } else {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Login failed.')));
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Parse Auth')),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: SingleChildScrollView(
          child: Column(
            children: [
              const Text(
                'Standard Authentication',
                style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
              ),
              TextField(
                controller: _usernameController,
                decoration: const InputDecoration(labelText: 'Username'),
              ),
              TextField(
                controller: _emailController,
                decoration: const InputDecoration(labelText: 'Email'),
              ),
              TextField(
                controller: _passwordController,
                decoration: const InputDecoration(labelText: 'Password'),
                obscureText: true,
              ),
              const SizedBox(height: 20),
              ElevatedButton(
                onPressed: _signUp,
                child: const Text('Sign Up'),
              ),
              ElevatedButton(
                onPressed: _login,
                child: const Text('Login'),
              ),
              const Divider(),
              const SizedBox(height: 20),
              const Text(
                'Third-Party Authentication',
                style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
              ),
              // Buttons for third-party authentication will be added here
            ],
          ),
        ),
      ),
    );
  }
}
// lib/screens/auth_screen.dart
import 'package:flutter/material.dart';
import '../services/auth_service.dart';

class AuthScreen extends StatefulWidget {
  @override
  _AuthScreenState createState() => _AuthScreenState();
}

class _AuthScreenState extends State<AuthScreen> {
  final TextEditingController _usernameController = TextEditingController();
  final TextEditingController _passwordController = TextEditingController();
  final TextEditingController _emailController = TextEditingController();
  final AuthService _authService = AuthService();

  void _signUp() async {
    var user = await _authService.signUp(
      _usernameController.text.trim(),
      _passwordController.text.trim(),
      _emailController.text.trim(),
    );
    if (user != null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('User created successfully!')));
    } else {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Sign up failed.')));
    }
  }

  void _login() async {
    var user = await _authService.login(
      _usernameController.text.trim(),
      _passwordController.text.trim(),
    );
    if (user != null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Login successful!')));
    } else {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Login failed.')));
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Parse Auth')),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: SingleChildScrollView(
          child: Column(
            children: [
              const Text(
                'Standard Authentication',
                style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
              ),
              TextField(
                controller: _usernameController,
                decoration: const InputDecoration(labelText: 'Username'),
              ),
              TextField(
                controller: _emailController,
                decoration: const InputDecoration(labelText: 'Email'),
              ),
              TextField(
                controller: _passwordController,
                decoration: const InputDecoration(labelText: 'Password'),
                obscureText: true,
              ),
              const SizedBox(height: 20),
              ElevatedButton(
                onPressed: _signUp,
                child: const Text('Sign Up'),
              ),
              ElevatedButton(
                onPressed: _login,
                child: const Text('Login'),
              ),
              const Divider(),
              const SizedBox(height: 20),
              const Text(
                'Third-Party Authentication',
                style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
              ),
              // Buttons for third-party authentication will be added here
            ],
          ),
        ),
      ),
    );
  }
}
﻿
Step 4 – Integrating Facebook Authentication
4.1. Set Up Facebook Developer Account
Create a Facebook App:
Go to Facebook for Developers and log in.
Click on "My Apps" and then "Create App".
Select "Consumer" as the app type and click "Next".
Fill in the App Name and Contact Email, then click "Create App".
Add Facebook Login to Your App:
In your app dashboard, navigate to "Add a Product" and select "Facebook Login".
Choose "Android" and/or "iOS" depending on your target platform.
Follow the setup steps provided by Facebook. You will need your app's Bundle Identifier for iOS and Package Name for Android.
Configure OAuth Redirect URI:
Set the OAuth Redirect URI to: https://parseapi.back4app.com/auth/facebook/callback
Obtain App ID and App Secret:
In your app dashboard, go to "Settings" > "Basic".
Note down the App ID and App Secret.
Add App ID and Secret to Back4App:
In Back4App dashboard, navigate to Server Settings > Authentication.
Under Facebook, input your App ID and App Secret.
4.2. Update auth_service.dart with Facebook Login
Add the following code to handle Facebook authentication:
Dart
// Add these imports at the top
import 'package:flutter_facebook_auth/flutter_facebook_auth.dart';

// Inside AuthService class
Map<String, dynamic> _facebookAuthData(
    String? accessToken, String? userId, DateTime? expirationDate) {
  return {
    'id': userId,
    'access_token': accessToken,
    'expiration_date': expirationDate?.toUtc().toIso8601String(),
  };
}

Future<ParseUser?> loginWithFacebook() async {
  final LoginResult result = await FacebookAuth.instance.login();
  if (result.status == LoginStatus.success) {
    final AccessToken accessToken = result.accessToken!;
    var user = ParseUser(null, null, null);
    var response = await user.loginWith(
      'facebook',
      _facebookAuthData(
        accessToken.token,
        accessToken.userId,
        accessToken.expires,
      ),
    );
    if (response.success) {
      return user;
    }
  }
  return null;
}
// Add these imports at the top
import 'package:flutter_facebook_auth/flutter_facebook_auth.dart';

// Inside AuthService class
Map<String, dynamic> _facebookAuthData(
    String? accessToken, String? userId, DateTime? expirationDate) {
  return {
    'id': userId,
    'access_token': accessToken,
    'expiration_date': expirationDate?.toUtc().toIso8601String(),
  };
}

Future<ParseUser?> loginWithFacebook() async {
  final LoginResult result = await FacebookAuth.instance.login();
  if (result.status == LoginStatus.success) {
    final AccessToken accessToken = result.accessToken!;
    var user = ParseUser(null, null, null);
    var response = await user.loginWith(
      'facebook',
      _facebookAuthData(
        accessToken.token,
        accessToken.userId,
        accessToken.expires,
      ),
    );
    if (response.success) {
      return user;
    }
  }
  return null;
}
﻿
4.3. Add Facebook Login Button to auth_screen.dart
Add the following button to your UI:
Dart
ElevatedButton(
  onPressed: () async {
    var user = await _authService.loginWithFacebook();
    if (user != null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Facebook login successful!')));
    } else {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Facebook login failed.')));
    }
  },
  child: const Text('Login with Facebook'),
),
ElevatedButton(
  onPressed: () async {
    var user = await _authService.loginWithFacebook();
    if (user != null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Facebook login successful!')));
    } else {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Facebook login failed.')));
    }
  },
  child: const Text('Login with Facebook'),
),
﻿
4.4. Platform-Specific Configurations
Android
Update your android/app/src/main/AndroidManifest.xml:
XML
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.auth_demo">

    <!-- Add this inside the <application> tag -->
    <meta-data android:name="com.facebook.sdk.ApplicationId"
        android:value="@string/facebook_app_id"/>
    <activity android:name="com.facebook.FacebookActivity"
        android:configChanges="keyboard|keyboardHidden|screenLayout|screenSize|orientation"
        android:label="@string/app_name" />

    <!-- Existing configurations -->
</manifest>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.auth_demo">

    <!-- Add this inside the <application> tag -->
    <meta-data android:name="com.facebook.sdk.ApplicationId"
        android:value="@string/facebook_app_id"/>
    <activity android:name="com.facebook.FacebookActivity"
        android:configChanges="keyboard|keyboardHidden|screenLayout|screenSize|orientation"
        android:label="@string/app_name" />

    <!-- Existing configurations -->
</manifest>
﻿
Add your Facebook App ID to android/app/src/main/res/values/strings.xml:
XML
<resources>
    <string name="app_name">AuthDemo</string>
    <string name="facebook_app_id">YOUR_FACEBOOK_APP_ID</string>
</resources>
<resources>
    <string name="app_name">AuthDemo</string>
    <string name="facebook_app_id">YOUR_FACEBOOK_APP_ID</string>
</resources>
﻿
iOS
Update your Info.plist file:
XML
<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>fbYOUR_FACEBOOK_APP_ID</string>
        </array>
    </dict>
</array>
<key>FacebookAppID</key>
<string>YOUR_FACEBOOK_APP_ID</string>
<key>FacebookDisplayName</key>
<string>AuthDemo</string>
<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>fbYOUR_FACEBOOK_APP_ID</string>
        </array>
    </dict>
</array>
<key>FacebookAppID</key>
<string>YOUR_FACEBOOK_APP_ID</string>
<key>FacebookDisplayName</key>
<string>AuthDemo</string>
﻿
Step 5 – Integrating Google Authentication
5.1. Set Up Google Developer Account
Create a Project in Google Cloud Console:
Go to Google Cloud Console and create a new project.
Configure OAuth Consent Screen:
Navigate to APIs & Services > OAuth consent screen.
Set up the consent screen with necessary scopes.
Create OAuth Client ID:
Go to Credentials > Create Credentials > OAuth client ID.
Choose Web application.
Add Authorized redirect URIs: https://parseapi.back4app.com/auth/google/callback
Note down the Client ID and Client Secret.
Add Client ID and Secret to Back4App:
In Back4App dashboard, under Server Settings > Authentication, input your Client ID and Client Secret for Google.
5.2. Update auth_service.dart with Google Login
Add the following code to handle Google authentication:
Dart
// Add this import at the top
import 'package:google_sign_in/google_sign_in.dart';

// Inside AuthService class
Map<String, dynamic> _googleAuthData(String? idToken, String? accessToken) {
  return {
    'id_token': idToken,
    'access_token': accessToken,
  };
}

Future<ParseUser?> loginWithGoogle() async {
  final GoogleSignIn googleSignIn = GoogleSignIn(
    scopes: ['email'],
  );
  final GoogleSignInAccount? googleUser = await googleSignIn.signIn();
  if (googleUser == null) {
    return null;
  }
  final GoogleSignInAuthentication googleAuth = await googleUser.authentication;
  var user = ParseUser(null, null, null);
  var response = await user.loginWith(
    'google',
    _googleAuthData(
      googleAuth.idToken,
      googleAuth.accessToken,
    ),
  );
  if (response.success) {
    return user;
  }
  return null;
}
// Add this import at the top
import 'package:google_sign_in/google_sign_in.dart';

// Inside AuthService class
Map<String, dynamic> _googleAuthData(String? idToken, String? accessToken) {
  return {
    'id_token': idToken,
    'access_token': accessToken,
  };
}

Future<ParseUser?> loginWithGoogle() async {
  final GoogleSignIn googleSignIn = GoogleSignIn(
    scopes: ['email'],
  );
  final GoogleSignInAccount? googleUser = await googleSignIn.signIn();
  if (googleUser == null) {
    return null;
  }
  final GoogleSignInAuthentication googleAuth = await googleUser.authentication;
  var user = ParseUser(null, null, null);
  var response = await user.loginWith(
    'google',
    _googleAuthData(
      googleAuth.idToken,
      googleAuth.accessToken,
    ),
  );
  if (response.success) {
    return user;
  }
  return null;
}
﻿
5.3. Add Google Login Button to auth_screen.dart
Add the following button to your UI:
Dart
ElevatedButton(
  onPressed: () async {
    var user = await _authService.loginWithGoogle();
    if (user != null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Google login successful!')));
    } else {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Google login failed.')));
    }
  },
  child: const Text('Login with Google'),
),
ElevatedButton(
  onPressed: () async {
    var user = await _authService.loginWithGoogle();
    if (user != null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Google login successful!')));
    } else {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Google login failed.')));
    }
  },
  child: const Text('Login with Google'),
),
﻿
5.4. Platform-Specific Configurations
Android
Add the following to your android/app/build.gradle file:
Text
dependencies {
    // Add this line
    implementation 'com.google.android.gms:play-services-auth:20.0.0'
    // Existing dependencies
}
dependencies {
    // Add this line
    implementation 'com.google.android.gms:play-services-auth:20.0.0'
    // Existing dependencies
}
﻿
Add your Google Client ID to android/app/src/main/res/values/strings.xml:
XML
<resources>
    <string name="app_name">AuthDemo</string>
    <string name="default_web_client_id">YOUR_GOOGLE_CLIENT_ID</string>
</resources>
<resources>
    <string name="app_name">AuthDemo</string>
    <string name="default_web_client_id">YOUR_GOOGLE_CLIENT_ID</string>
</resources>
﻿
Update your android/app/src/main/AndroidManifest.xml:
XML
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.auth_demo">
    <!-- Existing configurations -->
    <application>
        <!-- Existing configurations -->
        <meta-data android:name="com.google.android.gms.client.application_id"
            android:value="@string/default_web_client_id" />
    </application>
</manifest>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.auth_demo">
    <!-- Existing configurations -->
    <application>
        <!-- Existing configurations -->
        <meta-data android:name="com.google.android.gms.client.application_id"
            android:value="@string/default_web_client_id" />
    </application>
</manifest>
﻿
iOS
Add the reversed client ID to your Info.plist:
XML
<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>com.googleusercontent.apps.YOUR_CLIENT_ID</string>
        </array>
    </dict>
</array>
<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>com.googleusercontent.apps.YOUR_CLIENT_ID</string>
        </array>
    </dict>
</array>
﻿
Step 6 – Integrating Apple Authentication
6.1. Set Up Apple Developer Account
Register Your App:
Sign in to Apple Developer Portal and register your app.
Enable Sign in with Apple:
Under Identifiers, select your app and enable Sign in with Apple.
Create a Services ID:
Create a Services ID for your app.
Set the Redirect URI to: https://parseapi.back4app.com/auth/apple/callback
Generate a Client Secret:
Create a Sign in with Apple private key.
Use this key to generate a Client Secret.
Add Credentials to Back4App:
In Back4App dashboard, under Server Settings > Authentication, input your Services ID and Client Secret for Apple.
6.2. Update auth_service.dart with Apple Login
Add the following code to handle Apple authentication:
Dart
// Add this import at the top
import 'package:sign_in_with_apple/sign_in_with_apple.dart';
import 'dart:io' show Platform;

// Inside AuthService class
Map<String, dynamic> _appleAuthData(String? identityToken, String? userId) {
  return {
    'id': userId,
    'token': identityToken,
  };
}

Future<ParseUser?> loginWithApple() async {
  if (!Platform.isIOS) {
    // Sign in with Apple is only available on iOS
    return null;
  }
  final credential = await SignInWithApple.getAppleIDCredential(
    scopes: [
      AppleIDAuthorizationScopes.email,
      AppleIDAuthorizationScopes.fullName,
    ],
  );
  var user = ParseUser(null, null, null);
  var response = await user.loginWith(
    'apple',
    _appleAuthData(
      credential.identityToken,
      credential.userIdentifier,
    ),
  );
  if (response.success) {
    return user;
  }
  return null;
}
// Add this import at the top
import 'package:sign_in_with_apple/sign_in_with_apple.dart';
import 'dart:io' show Platform;

// Inside AuthService class
Map<String, dynamic> _appleAuthData(String? identityToken, String? userId) {
  return {
    'id': userId,
    'token': identityToken,
  };
}

Future<ParseUser?> loginWithApple() async {
  if (!Platform.isIOS) {
    // Sign in with Apple is only available on iOS
    return null;
  }
  final credential = await SignInWithApple.getAppleIDCredential(
    scopes: [
      AppleIDAuthorizationScopes.email,
      AppleIDAuthorizationScopes.fullName,
    ],
  );
  var user = ParseUser(null, null, null);
  var response = await user.loginWith(
    'apple',
    _appleAuthData(
      credential.identityToken,
      credential.userIdentifier,
    ),
  );
  if (response.success) {
    return user;
  }
  return null;
}
﻿
6.3. Add Apple Login Button to auth_screen.dart
Add the following button to your UI:
Dart
ElevatedButton(
  onPressed: () async {
    var user = await _authService.loginWithApple();
    if (user != null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Apple login successful!')));
    } else {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Apple login failed.')));
    }
  },
  child: const Text('Login with Apple'),
),
ElevatedButton(
  onPressed: () async {
    var user = await _authService.loginWithApple();
    if (user != null) {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Apple login successful!')));
    } else {
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('Apple login failed.')));
    }
  },
  child: const Text('Login with Apple'),
),
﻿
6.4. Platform-Specific Configurations
iOS Only
In Xcode, open your project and go to Signing & Capabilities.
Click on "+ Capability" and add "Sign in with Apple".
Ensure that your Bundle Identifier matches the one registered on the Apple Developer Portal.
Step 7 – Testing Your Application
Now that you've set up all authentication methods, you can run your app and test each login option.
7.1. Run the App
Bash
flutter run
flutter run
﻿
For iOS, you must run the app on a real device to test Sign in with Apple.
For Android, you can use an emulator or a physical device.
7.2. Test Standard Authentication
Enter a username, email, and password.
Tap "Sign Up" to create a new user.
Tap "Login" to log in with the created credentials.
7.3. Test Facebook Login
Tap "Login with Facebook".
A Facebook login screen will appear.
Log in with your Facebook credentials.
7.4. Test Google Login
Tap "Login with Google".
A Google sign-in screen will appear.
Log in with your Google account.
7.5. Test Apple Login (iOS Only)
Tap "Login with Apple".
The Apple sign-in prompt will appear.
Authenticate using your Apple ID.
Conclusion
In this tutorial, you successfully implemented standard email/password authentication and integrated third-party authentication methods (Facebook, Google, and Apple) into your Flutter app using the Parse SDK on Back4App. This setup enhances user experience by offering multiple convenient login options.
Next Steps
User Profiles: Extend the app to manage user profiles, allowing users to update their information.
Logout Functionality: Implement logout features for each authentication method.
Data Security: Secure your data by implementing role-based access control with Parse ACLs and Roles.
Error Handling: Improve error handling to provide more detailed feedback to users.
UI Enhancements: Customize the UI to match your app's branding and improve user experience.
Additional Resources
﻿Back4App Documentation﻿
﻿Parse Flutter SDK Guide﻿
﻿Flutter Official Documentation﻿
﻿Facebook for Developers﻿
﻿Google Identity Platform﻿
﻿Sign in with Apple Documentation﻿
Happy Coding!
Updated 14 Sep 2024
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