MKMapView上的模糊

import UIKit
import MapKit
import CoreImage

class ViewController: UIViewController {
    
    @IBOutlet weak var mapView: MKMapView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 截取MKMapView的截图
        let snapshot = mapView.takeSnapshot()
        
        // 创建模糊滤镜
        let filter = CIFilter(name: "CIGaussianBlur")
        filter?.setValue(snapshot, forKey: kCIInputImageKey)
        filter?.setValue(10, forKey: kCIInputRadiusKey)
        
        // 获取滤镜输出图像
        let outputImage = filter?.outputImage
        
        // 创建一个UIImageView来展示模糊效果
        let blurredImageView = UIImageView(frame: mapView.bounds)
        blurredImageView.image = UIImage(ciImage: outputImage!)
        
        // 将模糊视图添加到MKMapView上
        mapView.addSubview(blurredImageView)
    }
}

extension MKMapView {
    func takeSnapshot() -> CIImage {
        let renderer = UIGraphicsImageRenderer(bounds: bounds)
        let image = renderer.image { _ in
            drawHierarchy(in: bounds, afterScreenUpdates: true)
        }
        return CIImage(image: image)!
    }
}