isInRange method
Implementation
Future<TkfRange> isInRange(double lat, double lon, double distance) async {
Position p = await currentPosition;
double distanceBetween =
Geolocator.distanceBetween(p.latitude, p.longitude, lat, lon);
return TkfRange(
isInRange: distanceBetween <= distance,
latitude: p.latitude,
longitude: p.longitude,
distance: distanceBetween);
}