Flutter : how to check if app is opened by cliking on push notification or by clicking on app launcher icon

Question

I am trying to figure out if app is opened by clicking on push notification or by clicking on app launcher icon, scenario is that i want to check if app is opened by clicking push notification then i'll load data on home screen from cache other wise i need to get data from api.

i am using getInitialMessage() method but its not working in my case

here is my code

   Class NotificationService{ 
String? msg;
 bool fromNotification = false;
 final _firebaseMessaging = FirebaseMessaging.instance;
 Future<void> initNotification() async 
{
 RemoteMessage? initialMessage = await _firebaseMessaging.getInitialMessage(); 
 if (initialMessage != null) 
{ msg = initialMessage.toString();
 fromNotification = true;
 }
 }
 }

Answer 1

I have achieved this through the onMessageOpenedApp function. See my code below.

Define a PushNotificationHandler class as shown below:

class PushNotificationHandler {
final FirebaseMessaging _firebaseMessaging = FirebaseMessaging.instance;
final localNotifications = FlutterLocalNotificationsPlugin();
bool _openedFromNotification = false;
// Android Channel
final androidChannel = const AndroidNotificationChannel(
  'test_channel_name', "Test Channel",
  description: "This is a TEST Channel",
  importance: Importance.defaultImportance);

Future<bool> initialize() async {
// Initialize Firebase Messaging
await _firebaseMessaging.requestPermission();

// Get the FCM token to use when sending notifications
String? fcmToken;

if (Platform.isIOS) {
  fcmToken = await _firebaseMessaging.getAPNSToken() ?? "";
  final platform = localNotifications.resolvePlatformSpecificImplementation<
      IOSFlutterLocalNotificationsPlugin>();
} else if (Platform.isAndroid) {
  fcmToken = await _firebaseMessaging.getToken() ?? "";
  final platform = localNotifications.resolvePlatformSpecificImplementation<
      AndroidFlutterLocalNotificationsPlugin>();
  await platform?.createNotificationChannel(androidChannel);
}

// display the token so you can use it to send notifications
if (fcmToken != null) {
  print('FCMToken: ${fcmToken}');
}

// Handle notifications when the app is in the background
FirebaseMessaging.onBackgroundMessage(_handleBackgroundMessage);

// Handle notifications when the app is in the foreground
FirebaseMessaging.onMessage.listen((RemoteMessage message) {
  
});

// Handle notification clicks when the app is terminated
FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
  // Handle notification clicks here
  // Set a flag or send a message to the app indicating it was opened from a notification
  _openedFromNotification = true;
});

return _openedFromNotification;
}

The function initialize() will return bool.

Define your app as shown below:

class MyNotificationApp extends StatefulWidget {
@override
_MyNotificationAppState createState() => _MyNotificationAppState();
}
class _MyNotificationAppState extends State<MyNotificationApp> {
final PushNotificationHandler _pushNotificationHandler =
  PushNotificationHandler();
bool _appOpenedFromNotification = false;
@override
void initState() {
super.initState();
print('OPENING_APP');
_initializePushNotifications();
}
// Initialize the notifications
Future<void> _initializePushNotifications() async {
// Wait for the initialization to complete
bool result = await _pushNotificationHandler.initialize();
setState(() {
  _appOpenedFromNotification = result;
});
}
@override
Widget build(BuildContext context) {
return MaterialApp(
  title: 'My App',
  home: MyHomePage(appOpenedFromNotification: _appOpenedFromNotification),
);
}
}

In the MyHomePage widget, I am printing out how the app has been opened.

class MyHomePage extends StatelessWidget {
final bool appOpenedFromNotification;
const MyHomePage({super.key, required this.appOpenedFromNotification});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Home'),
  ),
  body: Center(
    child: Text(appOpenedFromNotification
        ? 'Opened from notification'
        : 'Opened from launcher'),
  ),
);
}
}

This should solve the issue you are having.