func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {

    switch overlay {
    case let overlay as MKPolyline:
        let renderer = MKPolylineRenderer(polyline: overlay)
        renderer.strokeColor = UIColor(red: 59, green: 164, blue: 252)
        renderer.lineWidth = 3
        return renderer
    default: return MKOverlayRenderer()
    }
}