Flutter Cancel Geolocator Listener - dart

Question

I am using Geolocator library to detect the location of the user. It works well however, I would like the listener to stop receiving any updates when the particular screen requesting the location updates is closed. I have no idea how to achieve this. Here is my code
class _CheckLoactionScreenState extends State<CheckLocationScreen>{
String _geoHash = "No Geo Hash";
String _placeId = "No Place Detected";
String _coordinates = "";
var geolocator = Geolocator();
var locationOptions = LocationOptions(accuracy: LocationAccuracy.high, distanceFilter: 10);
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
body: _body(),
);
}
_body(){
return Center(
child: Text(_geoHash),
),
);
}
_getLocation(){
geolocator.getPositionStream(locationOptions).listen(
(Position position) {
//print("${position.toString()}");
var newGeoHash = Geohash.encode(position.latitude, position.longitude).substring(0,8);
if(newGeoHash != _geoHash){
setState((){
_geoHash = newGeoHash;
});
}
_coordinates = position.toString();
print(_geoHash);
});
}
#override
void initState() {
super.initState();
_getLocation();
}
#override
void dispose() {
print("**** dispose");
geolocator.getPositionStream(null).listen(null);
super.dispose();
}
}
I attempt to cancel the listener in the dispose method but the listener still persists.

Answer 1

StreamSubscription _getPositionSubscription;
_getLocation(){
_getPositionSubscription = geolocator.getPositionStream(locationOptions).listen(
...
}
#override
void dispose() {
_getPositionSubscription?.cancel();
super.dispose();
}