basic flutter FCM example

main.dart

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

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(
    options: DefaultFirebaseOptions.currentPlatform,
  );
  await FirebaseMessaging.instance.requestPermission(
    alert: true,
    announcement: false,
    badge: true,
    carPlay: false,
    criticalAlert: false,
    provisional: false,
    sound: true,
  );
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  FirebaseMessaging firebaseMessaging = FirebaseMessaging.instance;
  String? _token;

  @override
  void initState() {
    super.initState();
    firebaseMessaging.getToken().then((token) => setState(() {
          debugPrint('!!! token $token');
          _token = token;
        }));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'Here is your token:',
            ),
            Text(
              '$_token',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
          ],
        ),
      ),
    );
  }
}