在Swift地图上的MKOverlay中添加模糊视图

import MapKit

class CustomOverlay: NSObject, MKOverlay {
    var coordinate: CLLocationCoordinate2D
    var boundingMapRect: MKMapRect
    
    init(coordinate: CLLocationCoordinate2D, boundingMapRect: MKMapRect) {
        self.coordinate = coordinate
        self.boundingMapRect = boundingMapRect
    }
}

class CustomOverlayRenderer: MKOverlayRenderer {
    override func draw(_ mapRect: MKMapRect, zoomScale: MKZoomScale, in context: CGContext) {
        guard let overlay = overlay as? CustomOverlay else {
            return
        }
        
        // 绘制模糊视图
        let blurEffect = UIBlurEffect(style: .light)
        let blurView = UIVisualEffectView(effect: blurEffect)
        blurView.frame = overlayRect(for: overlay.boundingMapRect)
        blurView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        blurView.alpha = 0.8
        
        // 将模糊视图添加到地图上
        if let mapView = self.mapView {
            mapView.addSubview(blurView)
        }
    }
}

class ViewController: UIViewController, MKMapViewDelegate {
    @IBOutlet weak var mapView: MKMapView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 设置地图视图的代理
        mapView.delegate = self
        
        // 创建自定义的MKOverlay对象
        let coordinate = CLLocationCoordinate2D(latitude: 37.7749, longitude: -122.4194)
        let overlay = CustomOverlay(coordinate: coordinate, boundingMapRect: MKMapRectWorld)
        
        // 将自定义的MKOverlay对象添加到地图上
        mapView.addOverlay(overlay)
    }
    
    // 地图视图的代理方法，返回自定义的MKOverlayRenderer子类对象
    func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
        if let customOverlay = overlay as? CustomOverlay {
            return CustomOverlayRenderer(overlay: customOverlay)
        }
        
        return MKOverlayRenderer(overlay: overlay)
    }
}