如何在折线中添加方向箭头？

Question

我想在mapkit中添加有向箭头折线。如何实现图像效果？

- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id<MKOverlay>)overlay
{
    MKOverlayRenderer *overlayRender = nil;
    MKPolylineRenderer *routeLineRender = [[MKPolylineRenderer alloc] initWithPolyline:overlay];
    routeLineRender.fillColor = RGB(134, 183, 98);
    routeLineRender.strokeColor = RGB(134, 183, 98);
    routeLineRender.lineWidth = 3;
    overlayRender = routeLineRender;
    return overlayRender;
}
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay
{
    MKOverlayView *overlayView = nil;
    MKPolylineView *routeLineView = [[MKPolylineView alloc] initWithPolyline:overlay];
    routeLineView.strokeColor = RGB(134, 183, 98);
    routeLineView.fillColor = RGB(134, 183, 98);
    routeLineView.lineWidth = 3;
    overlayView = routeLineView;
    return overlayView;
}