Flutter - Triggering StreamSubscription onData Manually

Question

I am using pedometer plugin in flutter, and one thing I noticed is that when I open the app after a while, the number of steps displayed does not update until I make steps while the app is opened in order to trigger onData method of the StreamSubscription. It is not setState problem because it updates every second.

Below is part of what I did related to this until now:

class _MyScreenState extends State<MyScreen>
    with AutomaticKeepAliveClientMixin<Page1>, WidgetsBindingObserver {
  StreamSubscription _subscription;
  final Store<AppState> store;

  _MyScreenState(this.store, this.pedometer);

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    setUpPedometer();

}

  void setUpPedometer() {
    _subscription = pedometer.stepCountStream
        .listen(_onData, onError: _onError, cancelOnError: true);
  }

  @override
  Future<Null> didChangeAppLifecycleState(AppLifecycleState state) async {
    if (state == AppLifecycleState.resumed) {
      await resumeCallBack();
    }
  }

  resumeCallBack() {
     // here, I am looking for a way to trigger onData method
  }

  void _onData(int stepCountValue) async {
    print("stepCountValue : ${stepCountValue}");
    store.dispatch(UpdateStepsAction(
        steps: stepCountValue));
}

}

Answer 1

import 'dart:async';
import 'package:pedometer/pedometer.dart';

class PedometerController{
  static Future<int> getStepsFromPedometer() async{

    StreamController<int> streamHelper = new StreamController();
    var pedometer = Pedometer();
    pedometer.pedometerStream.listen((v){
      streamHelper.sink.add(v);
      streamHelper.close();
    });
    return await whenTrue(streamHelper.stream);
  }

  static Future<int> whenTrue(Stream<int> source) {
    return source.firstWhere((int item) => item > -1);
  }
}