android – Flutter: how to handle notifications actions with app in background

Long story short: I’m trying to get notifications actions to work in Flutter when the app is closed (killed) in Android and iOS.

I’m developing with:

• Flutter version 3.16.9
• Dart version 3.2.6
• flutter_local_notifications package version 16.3.2

I’m using the flutter_local_notifications plugin that has a onDidReceiveBackgroundNotificationResponse callback, but no matter how I set it, the compiler returns this error:

The backgroundHandler needs to be either a static function or a top level function to be accessible as a Flutter entry point.

My main.dart is now set this way:

import 'package:flutter_local_notifications/flutter_local_notifications.dart';

const String channelId = 'channel_id';
const String channelName="Channel Name";
const String darwinNotificationActionCategory = 'plainCategory';
FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();


@pragma('vm:entry-point')
void notificationTapBackground(NotificationResponse notificationResponse) {
  print('Test entry point');
}

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  flutterLocalNotificationsPlugin.resolvePlatformSpecificImplementation<AndroidFlutterLocalNotificationsPlugin>()?.requestNotificationsPermission();
  flutterLocalNotificationsPlugin.resolvePlatformSpecificImplementation<IOSFlutterLocalNotificationsPlugin>()?.requestPermissions(
      alert: true,
      badge: true,
      sound: true
  );

  const AndroidInitializationSettings initializationSettingsAndroid = AndroidInitializationSettings('app_icon');
  final DarwinInitializationSettings initializationSettingsDarwin = DarwinInitializationSettings(
      requestAlertPermission: true,
      requestBadgePermission: true,
      requestSoundPermission: true,
      notificationCategories: [
        DarwinNotificationCategory(
            darwinNotificationActionCategory,
            actions: <DarwinNotificationAction>[
              DarwinNotificationAction.plain(
                'action',
                'Action!',
                options: <DarwinNotificationActionOption>{
                  DarwinNotificationActionOption.foreground,
                },
              ),
            ],
            options: <DarwinNotificationCategoryOption>{
              DarwinNotificationCategoryOption.hiddenPreviewShowTitle,
            }
        )
      ],
      onDidReceiveLocalNotification: (int id, String? title, String? body, String? payload) async {
        NotificationService.onNotificationClick(id);
      }
  );

  final InitializationSettings initializationSettings = InitializationSettings(
      android: initializationSettingsAndroid,
      iOS: initializationSettingsDarwin
  );

  await flutterLocalNotificationsPlugin.initialize(
      initializationSettings,
      onDidReceiveNotificationResponse: (NotificationResponse notificationResponse) => NotificationService.onNotificationClick(notificationResponse.actionId ?? ''),
      onDidReceiveBackgroundNotificationResponse: (NotificationResponse notificationResponse) => notificationTapBackground(notificationResponse)
  );

  [...]
}

As you can see, the notificationTapBackground callback is a top-level function and it’s still not working. I tried also creating it as a static method but it doesn’t work.

Can anyone tell me what I’m doing wrong?

Thanks in advance!