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Sample Flutter Client Implementation

main.dart

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

/// Background message handler for Firebase Cloud Messaging.
@pragma('vm:entry-point')
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
await Firebase.initializeApp();
}

Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized(); // Ensure Flutter is initialized

await Firebase.initializeApp(
options: DefaultFirebaseOptions.currentPlatform,
);

FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);

await _initializeAnalytics();

runApp(const MyApp());
}

/// Initializes Firebase Analytics and enables analytics collection.
Future<void> _initializeAnalytics() async {
FirebaseAnalytics analytics = FirebaseAnalytics.instance;
await analytics.setAnalyticsCollectionEnabled(true);
}

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

@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
),
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> {
int _counter = 0;
String? _fcmToken;

@override
void initState() {
super.initState();
_initializeFirebaseMessaging();
}

/// Initializes Firebase Messaging and retrieves the FCM token.
Future<void> _initializeFirebaseMessaging() async {
FirebaseMessaging messaging = FirebaseMessaging.instance;

await messaging.requestPermission(
alert: true,
badge: true,
sound: true,
provisional: true,
);

// Get the initial FCM token
String? token = await messaging.getToken();
_updateFcmToken(token);

// Handle token refresh
FirebaseMessaging.instance.onTokenRefresh.listen(_updateFcmToken);
}

/// Updates the FCM token and prints it for debugging.
/// TODO(): Store the updated token along with the user_id on the server.
void _updateFcmToken(String? token) {
setState(() => _fcmToken = token);
debugPrint("FCM Token: $_fcmToken");
}

void _incrementCounter() {
setState(() => _counter++);
}

/// UI code below.
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: Theme.of(context).colorScheme.inversePrimary,
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
const Text('You have pushed the button this many times:'),
Text(
'$_counter',
style: Theme.of(context).textTheme.headlineMedium,
),
const SizedBox(height: 20),
Text(
_fcmToken ?? "Fetching FCM token...",
style: Theme.of(context).textTheme.bodyMedium,
textAlign: TextAlign.center,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: const Icon(Icons.add),
),
);
}
}

firebase_options.dart

import 'package:firebase_core/firebase_core.dart' show FirebaseOptions;
import 'package:flutter/foundation.dart'
show defaultTargetPlatform, TargetPlatform;

class DefaultFirebaseOptions {
static FirebaseOptions get currentPlatform {
switch (defaultTargetPlatform) {
case TargetPlatform.android:
return android;
default:
throw UnsupportedError(
'DefaultFirebaseOptions are not supported for this platform.',
);
}
}

static const FirebaseOptions android = FirebaseOptions(
apiKey: '<TODO(): Add API Key>',
appId: '<TODO(): Add App Id>',
messagingSenderId: '<TODO(): Add messaging sender id>',
projectId: 'demo',
storageBucket: 'demo.firebasestorage.app',
);
}

.flutter-plugins (generated file)

Install plugins:
https://firebase.google.com/docs/analytics/get-started?platform=flutter
https://firebase.google.com/docs/cloud-messaging/flutter/client
# This is a generated file; do not edit or check into version control.
firebase_analytics=xxxxxxxxxx
firebase_analytics_web=xxxxxxxxxx
firebase_core=xxxxxxxxxx
firebase_core_web=xxxxxxxxxx
firebase_messaging=xxxxxxxxxx
firebase_messaging_web=xxxxxxxxxx