如何在MKMapView中将用户当前位置蓝点转换为自定义图像

class CustomAnnotationView: MKAnnotationView {
    override init(annotation: MKAnnotation?, reuseIdentifier: String?) {
        super.init(annotation: annotation, reuseIdentifier: reuseIdentifier)
        
        // 设置自定义图像
        self.image = UIImage(named: "customImage")
        
        // 设置图像的大小
        self.frame = CGRect(x: 0, y: 0, width: 30, height: 30)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
    if annotation is MKUserLocation {
        // 创建自定义的MKAnnotationView
        let annotationView = CustomAnnotationView(annotation: annotation, reuseIdentifier: "CustomAnnotation")
        
        return annotationView
    }
    
    return nil
}

class MapViewController: UIViewController, MKMapViewDelegate {
    @IBOutlet weak var mapView: MKMapView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 设置地图视图的代理
        mapView.delegate = self
        
        // 显示用户当前位置
        mapView.showsUserLocation = true
    }
    
    // MKMapViewDelegate方法
    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
        if annotation is MKUserLocation {
            // 创建自定义的MKAnnotationView
            let annotationView = CustomAnnotationView(annotation: annotation, reuseIdentifier: "CustomAnnotation")
            
            return annotationView
        }
        
        return nil
    }
}