How to change the callback interval of foreground service?

[joeldunamis]

Is there any way to change the interval of the callback if a certain requirement is met during the callback? I tried calling the init function with a different interval and restarting the service, but it doesn't change from the initial interval.

I didn't really change many parts of the sample code, but here it is:

Future<void> initializeForegroundTask(int interval) async {
    T? _ambiguate<T>(T? value) => value;

    int intervalValue = interval;

    GeneralFunctions.initForegroundTask(intervalValue).then((value) {
      _ambiguate(WidgetsBinding.instance)?.addPostFrameCallback((_) async {
        // You can get the previous ReceivePort without restarting the service.
        if (await FlutterForegroundTask.isRunningService) {
          final newReceivePort = await FlutterForegroundTask.receivePort;
          GeneralFunctions.registerReceivePort(newReceivePort);
        }
      });

      startForegroundTask();
    });
  }

  static Future<void> initForegroundTask(int interval) async {
    await FlutterForegroundTask.init(
      androidNotificationOptions: GeneralVariables.androidNotificationOptions,
      iosNotificationOptions: GeneralVariables.iosNotificationOptions,
      foregroundTaskOptions: ForegroundTaskOptions(
        interval: interval,
        autoRunOnBoot: true,
        allowWifiLock: true,
      ),
      printDevLog: true,
    );
  }

  static Future<bool> startForegroundTask() async {
    if (!await FlutterForegroundTask.canDrawOverlays) {
      final isGranted =
          await FlutterForegroundTask.openSystemAlertWindowSettings();
      if (!isGranted) {
        print('SYSTEM_ALERT_WINDOW permission denied!');
        return false;
      }
    }

    ReceivePort? receivePort;
    if (await FlutterForegroundTask.isRunningService) {
      print("RESTARTING");
      receivePort = await FlutterForegroundTask.restartService();
    } else {
      print("STARTING");
      receivePort = await FlutterForegroundTask.startService(
        notificationTitle: 'Title',
        notificationText: 'Text',
        callback: startCallback,
      );
    }

    return GeneralFunctions.registerReceivePort(receivePort);
  }

And here's the code for the handler and callback function:

void startCallback() {
  FlutterForegroundTask.setTaskHandler(MyTaskHandler());
}

class MyTaskHandler extends TaskHandler {
  SendPort? _sendPort;

  @override
  Future<void> onStart(DateTime timestamp, SendPort? sendPort) async {
    _sendPort = sendPort;
  }

  @override
  Future<void> onEvent(DateTime timestamp, SendPort? sendPort) async {
  
    FlutterForegroundTask.updateService(
        notificationTitle: 'Updated Title',
        notificationText:  'Updated Text');

    await GeneralFunctions.initializeForegroundTask(20000);
  }

  @override
  Future<void> onDestroy(DateTime timestamp, SendPort? sendPort) async {
    await FlutterForegroundTask.clearAllData();
  }

  @override
  void onButtonPressed(String id) {
    print('onButtonPressed >> $id');
  }

  @override
  void onNotificationPressed() {
    _sendPort?.send('onNotificationPressed');
  }
}

[gri38]

Hello. I have the same question.

I tried several things, but no one works: In _receivePort listening function that handles messages from onEvent::_sendPort?.send(message):

1. I tried to _closeReceivePort(), then _stopForegroundTask(), then _initForegroundTask with a different interval, and finally _startForegroundTask
2. Yhe same without _closeReceivePort
3. I tried to only _initForegroundTask again with another interval and _startForegroundTask (so that it restarts)
4. I also tried 1, 2 and 3 in a Timer callbcak function called after the _receivePort listening function has finished (mutex protection)

For 3: the foreground task still work, but at the same interval. For 1: I don't really understand, it seems the foreground task still runs, but my _receivePort listening function is not called anymore.

What would you advise to do change the OnEvent interval ?

Thanks a lot for your work.

[gri38]

Hi @joeldunamis . Did you solve this problem ? Or did you workaround ?

[Dev-hwang]

Upgrade to 6.0.0

You can change the interval using foregroundTaskOptions in FlutterForegroundTask.updateService function.

@override
Future<void> onRepeatEvent(DateTime timestamp, SendPort? sendPort) async {
  if (_eventCount == 10) {
    FlutterForegroundTask.updateService(
      foregroundTaskOptions: const ForegroundTaskOptions(interval: 1000),
    );
  } else {
    _eventCount++;
  }
}

[gri38]

Hi @Dev-hwang Wonderful, thanks a lot. I'll try.