Implementing Firebase Integration

flutter create my_flutter_app
cd my_flutter_app
flutter pub add firebase_core
flutter pub add cloud_firestore

dependencies:
  firebase_core: ^2.15.0
  cloud_firestore: ^4.8.0
  firebase_auth: ^4.6.0

import 'package:firebase_core/firebase_core.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

import UIKit
import Firebase

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
  func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    FirebaseApp.configure()
    return true
  }
}

// Import Firebase Auth package
import 'package:firebase_auth/firebase_auth.dart';

// Initialize FirebaseAuth instance
final FirebaseAuth auth = FirebaseAuth.instance;

// Sign in with email and password
Future<UserCredential> signInWithEmail(String email, String password) async {
  try {
    final UserCredential userCredential = await auth.signInWithEmailAndPassword(
      email: email,
      password: password,
    );
    return userCredential;
  } catch (e) {
    print('Sign-in error: $e');
    rethrow;
  }
}

// Create a new user with email and password
Future<UserCredential> createUserWithEmail(String email, String password) async {
  try {
    final UserCredential userCredential = await auth.createUserWithEmailAndPassword(
      email: email,
      password: password,
    );
    return userCredential;
  } catch (e) {
    print('User creation error: $e');
    rethrow;
  }
}

// Import Google Sign-In package
import 'package:google_sign_in/google_sign_in.dart';

// Initialize Google Sign-In
final GoogleSignIn googleSignIn = GoogleSignIn();

// Handle sign-in with Google
Future<UserCredential> signInWithGoogle() async {
  try {
    final GoogleSignInAccount? googleUser = await googleSignIn.signIn();
    if (googleUser == null) return Future.error('Sign-in cancelled');

    final GoogleSignInAuthentication googleAuth = await googleUser.authentication;
    final OAuthCredential credential = GoogleAuthProvider.credential(
      accessToken: googleAuth.accessToken,
      idToken: googleAuth.idToken,
    );

    final UserCredential userCredential = await auth.signInWithCredential(credential);
    return userCredential;
  } catch (e) {
    print('Google sign-in error: $e');
    rethrow;
  }
}

// Import the Firebase package
import 'package:cloud_firestore/cloud_firestore.dart';

// Initialize Firestore
final FirebaseFirestore db = FirebaseFirestore.instance;

// Reference to a collection
CollectionReference users = db.collection('users');

// Query users with age greater than 25
QuerySnapshot querySnapshot = await db.collection('users')
    .where('age', isGreaterThan: 25)
    .get();

// Iterate through results
for (var doc in querySnapshot.docs) {
  print(doc['name']);
}

// Listen for real-time changes
db.collection('users').snapshots().listen((snapshot) {
  for (var doc in snapshot.docs) {
    print('User: ${doc['name']}');
  }
});

// Import the Firebase Storage package
import 'package:firebase_storage/firebase_storage.dart';

// Create a reference to the file you want to upload
StorageReference storageRef = FirebaseStorage.instance.ref().child('images/my_image.jpg');

// Upload the file
Future<StorageTaskSnapshot> uploadTask = storageRef.putFile(File('/path/to/my/image.jpg'));

// Handle the result
uploadTask.then((StorageTaskSnapshot snapshot) {
  print('Upload completed');
});

// Get the download URL for a file
StorageReference storageRef = FirebaseStorage.instance.ref().child('images/my_image.jpg');

storageRef.getDownloadURL().then((String url) {
  print('Download URL: $url');
});

import 'package:firebase_messaging/firebase_messaging.dart';

Future<void> requestNotificationPermission() async {
  NotificationSettings settings = await FirebaseMessaging.requestPermission(
    alert: true,
    announcement: false,
    badge: true,
    carPlay: false,
    criticalAlert: false,
    provisional: false,
    sound: true,
  );

  if (settings.authorizationStatus == AuthorizationStatus.authorized) {
    print('User granted permission');
  } else if (settings.authorizationStatus == AuthorizationStatus.denied) {
    print('User denied permission');
  }
}

import 'package:firebase_messaging/firebase_messaging.dart';

void main() {
  FirebaseMessaging.onMessage.listen((RemoteMessage message) {
    print('Got a message whilst in the foreground!');
    print('Message data: ${message.data}');
  });
}

import 'package:firebase_messaging/firebase_messaging.dart';

Future<void> backgroundHandler(RemoteMessage message) async {
  await Firebase.initializeApp();
  print('Handling a background message: ${message.messageId}');
}

void main() {
  FirebaseMessaging.onBackgroundMessage(backgroundHandler);
}

import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_analytics/firebase_analytics.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}