final GeolocationResult result = await Geolocation.isLocationOperational();
if(result.isSuccessful) {
  // location service is enabled, and location permission is granted
} else {
  // location service is not enabled, restricted, or location permission is denied
}

final GeolocationResult result = await Geolocation.requestLocationPermission(const LocationPermission(
  android: LocationPermissionAndroid.fine,
  ios: LocationPermissionIOS.always,
));

if(result.isSuccessful) {
  // location permission is granted (or was already granted before making the request)
} else {
  // location permission is not granted
  // user might have denied, but it's also possible that location service is not enabled, restricted, and user never saw the permission request dialog 
}

// best option for most cases
StreamSubscription<LocationResult> subscription = Geolocation.currentLocation(accuracy: LocationAccuracy.best).listen((result) {
  if(result.isSuccessful) {
    Double latitude = result.location.latitude;
    // todo with result
  }
});

// force a single location update
StreamSubscription<LocationResult> subscription = Geolocation.currentLocation(accuracy: LocationAccuracy.best).listen((result) {
  // todo with result
});

// get last known location, which is a future rather than a stream
LocationResult result = await Geolocation.lastKnownLocation();

StreamSubscription<LocationResult> subscription = Geolocation.locationUpdates(
    accuracy: LocationAccuracy.best,
    displacementFilter: 10.0, // in meters
    inBackground: true, // by default, location updates will pause when app is inactive (in background). Set to `true` to continue updates in background. 
  )
  .listen((result) {
    if(result.isSuccessful) {
      // todo with result
    }
  });


// cancelling subscription will also stop the ongoing location request
subscription.cancel();

LocationResult result = await Geolocation.lastKnownLocation();

if (result.isSuccessful) {
  // location request successful, location is guaranteed to not be null 
  double lat = result.location.latitude;
  double lng = result.location.longitude;
} else {
  switch (result.error.type) {
    case GeolocationResultErrorType.runtime:
      // runtime error, check result.error.message
      break;
    case GeolocationResultErrorType.locationNotFound:
      // location request did not return any result
      break;
    case GeolocationResultErrorType.serviceDisabled:
      // location services disabled on device
      // might be that GPS is turned off, or parental control (android) 
      break;
    case GeolocationResultErrorType.permissionDenied:
      // user denied location permission request
      // rejection is final on iOS, and can be on Android
      // user will need to manually allow the app from the settings
      break;
    case GeolocationResultErrorType.playServicesUnavailable:
      // android only
      // result.error.additionalInfo contains more details on the play services error
      switch(result.error.additionalInfo as GeolocationAndroidPlayServices) {
        // do something, like showing a dialog inviting the user to install/update play services
        case GeolocationAndroidPlayServices.missing:
        case GeolocationAndroidPlayServices.updating:
        case GeolocationAndroidPlayServices.versionUpdateRequired:
        case GeolocationAndroidPlayServices.disabled:
        case GeolocationAndroidPlayServices.invalid:
      }
    break;
  }
}