how to make flutter cubit listen to changes in background?

Question

so i want to know how i can make the flutter cubit bloc works in background for flutter ?

i tried to use this code to listen to changes and emit new location it's work only in forground

  location.onLocationChanged.listen((LocationData currentLocation) async {
     emit(currentLocation);
  });

even when i set enablebackground the cubit will stop working

location.enableBackgroundMode(enable: true);

is there a better way to implement it ?

Answer 1

this is what i end up doing , it's worked well , just move your logic away from blocbuilder and bloclistenr

Location state

// ignore_for_file: public_member_api_docs, sort_constructors_first
part of 'location_cubit.dart';

abstract class LocationState extends Equatable {
  @override
  List<Object> get props => [];
}

class LocationInitial extends LocationState {
  final double lat;
  final double lng;
  LocationInitial({
    required this.lat,
    required this.lng,
  });
  @override
  List<Object> get props => [lat, lng];
}

class Locationloading extends LocationState {
  Locationloading();
}

location cubit

import 'dart:async';
// ignore: depend_on_referenced_packages
import 'package:bloc/bloc.dart';
import 'package:equatable/equatable.dart';
import 'package:hive/hive.dart';
import 'package:location/location.dart';

part 'location_state.dart';

class LocationCubit extends Cubit<LocationState> {
  late StreamSubscription<LocationData> control;
  Location elocation = Location();
  LocationCubit() : super(LocationInitial(lat: 0, lng: 0)) {
    print("Init");

    elocation.changeSettings(interval: 8000, distanceFilter: 20);
    control = elocation.onLocationChanged
        .listen((LocationData location) => {inc(location)});
  }

  void inc(LocationData location) {
    /* This will get called on background and forground too
     , BUT UI get updated only in Forground 
     ( so all BlocBuilder / BlocListner will not be invoked in background
     all your logic should be here ( like call http or something)
     and when your app is back to forground it's will work ");
    */
    print("called on backgroud and forground");
    String nice = Hive.box('myBox').get('name');
    print(nice);
    emit(LocationInitial(
        lat: location.latitude!.toDouble(),
        lng: location.longitude!.toDouble()));
  }

  void pause() async {
    print("should be paused");
    emit(Locationloading());
    await elocation.enableBackgroundMode(enable: false);
    print("should be ok paused");
    control.pause();
    emit(LocationInitial(lat: 0, lng: 0));
  }

  void cont() async {
    emit(Locationloading());
    print("should be cont");
    await elocation.enableBackgroundMode(enable: true);
    print("should be ok cont");
    LocationData loca = await elocation.getLocation();
    control.resume();
    (LocationInitial(
        lat: loca.latitude!.toDouble(), lng: loca.longitude!.toDouble()));
  }

  @override
  Future<void> close() async {
    print("should be called");
    await elocation.enableBackgroundMode(enable: false);
    control.cancel();
    print("should be bye");
    return super.close();
  }
}