如何在Swift iOS中更改MKUserLocation批注中的默认图像

class CustomUserLocationAnnotationView: MKAnnotationView {
    // 在这里自定义批注视图的外观
}

override init(annotation: MKAnnotation?, reuseIdentifier: String?) {
    super.init(annotation: annotation, reuseIdentifier: reuseIdentifier)
    
    // 设置自定义图像
    self.image = UIImage(named: "custom_user_location_image")
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

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

class ViewController: UIViewController, MKMapViewDelegate {
    @IBOutlet weak var mapView: MKMapView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 设置MKMapView的delegate为自身
        mapView.delegate = self
    }
    
    // 实现其他必要的方法和功能
}