var distance = 0.0
@IBOutlet weak var mapView: MKMapView!



lazy var locationManager: CLLocationManager = {
    var _locationManager = CLLocationManager()
    _locationManager.delegate = self
    _locationManager.desiredAccuracy = kCLLocationAccuracyBest
    _locationManager.activityType = .fitness
    _locationManager.distanceFilter = 10.0
    return _locationManager}()
lazy var locations = [CLLocation]()



extension GPSTracker: CLLocationManagerDelegate {
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    for location in locations {
        let howRecent = location.timestamp.timeIntervalSinceNow
        let accuracy = location.horizontalAccuracy
        if abs(howRecent) < 10 && accuracy < 10 && accuracy > 0 && location.verticalAccuracy > 0 {
            let region = MKCoordinateRegionMakeWithDistance(location.coordinate, 500, 500)
            mapView.setRegion(region, animated: true)
            if self.locations.count > 0 {
                    distance += location.distance(from: self.locations.last!)
                    var coords = [CLLocationCoordinate2D]()
                    coords.append(self.locations.last!.coordinate)
                    coords.append(location.coordinate)
                    mapView.add(MKPolyline(coordinates: &coords, count: coords.count))}
            self.locations.append(location)}}}