Flutter Push Notification / APNs with Firebase Cloud Messaging (FCM) Example

main.dart

import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/material.dart';

import 'firebase_options.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);

  runApp(const MaterialApp(home: App()));
}

class App extends StatefulWidget {
  const App({Key? key}) : super(key: key);
  @override
  State<StatefulWidget> createState() => _AppState();
}

Future<void> _firebaseMessagingHandler(RemoteMessage message) async {
  debugPrint('Notification: ${message.notification?.title ?? ''}');
}

class _AppState extends State<App> {
  String _message = '';
  @override
  void initState() {
    super.initState();
    _initFirebase();
    _setupInteractedMessage();
  }

  Future<void> _initFirebase() async {
    bool allow = await _requestPermission();

    if (!allow) return;

    debugPrint('device token = ${await FirebaseMessaging.instance.getToken()}');

    FirebaseMessaging.onMessage.listen(_firebaseMessagingHandler);
    FirebaseMessaging.onBackgroundMessage(_firebaseMessagingHandler);
  }

  void _setupInteractedMessage() async {
    // Read messages which caused the application to open from
    // a terminated state.
    FirebaseMessaging messaging = FirebaseMessaging.instance;
    RemoteMessage? initialMessage = await messaging.getInitialMessage();
    setState(() => _message = initialMessage?.notification?.title ?? 'No');

    // Also handle any interaction when the app is in the background
    FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
      setState(() => _message = message.notification?.title ?? 'No');
    });
  }

  Future<bool> _requestPermission() async {
    FirebaseMessaging messaging = FirebaseMessaging.instance;
    NotificationSettings settings = await messaging.requestPermission(
      alert: true,
      badge: true,
      provisional: false,
      sound: true,
    );

    return (settings.authorizationStatus == AuthorizationStatus.authorized ||
        settings.authorizationStatus == AuthorizationStatus.provisional);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(body: Center(child: Text(_message)));
  }
}