noti.dart

Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  if (message.data['message'] == 'Calling message') {
    showCallNotification(
        3, message.data['chatroomid'], message.data['userName']);
  }

  await Firebase.initializeApp();
}

void main() async {

  WidgetsFlutterBinding.ensureInitialized();

  await firebase_core.Firebase.initializeApp();

  FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);

  runApp(MyApp());
}