FlutterJNI was detached from native C++

[darshansatra1]

Error: W/FlutterJNI(31092): Tried to send a platform message to Flutter, but FlutterJNI was detached from native C++. Could not send. Channel: step_count. Response ID: 0

When I closed the app, sometimes while walking the debug console shows me this message. Can you help me with this, why I'm getting this error?

[Dev-hwang]

@darshansatra1

This error occurs when you subscribe to a stream and do not unsubscribe from the stream when exiting the app. Be sure to call the cancel function in the onDestroy function.

NOTE: Code to get a stream like Geolocator.getPositionStream() should be called inside the callback function. The same goes for the positionStream variable. Do not try to use this with main isolate by declaring it as a global variable or static.

void startCallback() {
  final positionStream = Geolocator.getPositionStream();
  StreamSubscription<Position>? streamSubscription;

  FlutterForegroundTask.initDispatcher((timestamp, sendPort) async {
    if (streamSubscription != null) return;

    streamSubscription = positionStream.listen((event) {
      print('timestamp: ${timestamp.toString()}');

      FlutterForegroundTask.update(
          notificationTitle: 'Current Position',
          notificationText: '${event.latitude}, ${event.longitude}');
    });
  }, onDestroy: (timestamp) async {
    await streamSubscription?.cancel();  // here
    print('Dispatcher is dead.. x_x');
  });
}

The implementation process is as follows:

1. Upgrade flutter_foreground_task: ^2.1.0
2. Create and subscribe to the stream inside the callback as in the example above. Don't try to use the same stream for background isolate and main isolate.
3. Check How to use-3 in the README file.
4. When the FlutterForegroundTask.start() function is called successfully, it returns a ReceivePort object. Subscribe to ReceivePort.
5. Send data to main isolate using sendPort.send provided by FlutterForegroundTask.initDispatcher.
6. Implement the ReceivePort you subscribed to in step 4 in more detail. Update your UI or process data here.
7. Be sure to call receivePort?.close() when the app is closed.
8. When the app restarts, call FlutterForegroundTask.stop() and go back to step 4.

[darshansatra1]

Yess I followed the instructions and now it's working awesome.

[behradkhadem]

As it looks initDispacher has been removed. IDE gives me this:

The method 'initDispatcher' isn't defined for the type 'FlutterForegroundTask'.
Try correcting the name to the name of an existing method, or defining a method named 'initDispatcher'.

What is the alternative version of the code above for flutter_foreground_task: ^3.5.5 ?