GPS off message, and continous location update flutter - flutter

Question

i made an app which uses the geolocator package to check for GPS and get the location of the user, and i use the provider package to handle the state. The problem is, when the GPS is switched off, a red screen appears that says the latitude was null, i would like to implement a screen to tell the user to switch on the GPS, and update the location accordingly.
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_map/flutter_map.dart';
import 'package:geolocator/geolocator.dart';
import 'package:latlong/latlong.dart';
class MapState with ChangeNotifier {
bool locationServiceActive = true;
MapController _mapController;
MapController get mapController => _mapController;
static var _initialPosition;
var _lastPosition = _initialPosition;
LatLng get initialPosition => _initialPosition;
LatLng get lastPosition => _lastPosition;
MapState(){
checkGPS();
_getUserLocation();
}
checkGPS() async{
bool conn = await Geolocator().isLocationServiceEnabled();
if(conn == false){
locationServiceActive = false;
} else {
locationServiceActive = true;
}
notifyListeners();
}
void _getUserLocation() async{
Position position = await Geolocator().getCurrentPosition(desiredAccuracy: LocationAccuracy.high);
print("/////////////////////////////////////////////////////////////////////////////////position");
print(position);
_initialPosition = LatLng(position.latitude, position.longitude);
notifyListeners();
}
}
update:-
i changed my _getUserLocation function to a stream, which works much better if the user switched on or off the gps (and it uses the last known location if the gps is off)... but it doesn't print the statement in the terminal if the position is null which is weird, only when there is lat and lng!!!
here is the modification i made...
void _getUserLocation() async{
Position position = await Geolocator().getCurrentPosition(desiredAccuracy: LocationAccuracy.high);
var geolocator = Geolocator();
var locationOptions = LocationOptions(accuracy: LocationAccuracy.high, distanceFilter: 10);
StreamSubscription<Position> positionStream = geolocator.getPositionStream(locationOptions).listen(
(Position position) {
print("/////////////////////////////////////////////////////////////////////////// position");
print(position == null ? 'Unknown' : position.latitude.toString() + ', ' + position.longitude.toString());
});
_initialPosition = LatLng(position.latitude, position.longitude);
notifyListeners();
}

Answer 1

If you want to notify the user about the GPS, you can use something like this
#override
void initState() {
super.initState();
initPlatformState();
location.onLocationChanged.listen((result) {
currentLocation = result;
// your code
});
});
}
void initPlatformState() async {
LocationData currentLocation;
try {
currentLocation = await location.getLocation();
error = "";
} on PlatformException catch (e) {
if (e.code == 'PERMISSION_DENIED')
error = 'Permission Denied';
else if (e.code == 'PERMISSION_DENIED_NEVER_ASK')
error =
'Permission denied - please ask the user to enable it from the app settings';
currentLocation = null;
}
setState(() {
currentLocation = currentLocation;
});
}
Here, you are listening to the location stream if enabled. In case it is not then it throws an error. The package being used here is location