swift高斯模糊的自定义view

var bgImage = UIImageView()
    var backButton = UIButton()
    var titleLabel = UILabel()
    let screen_h = UIScreen.main.bounds.height
    let screen_w = UIScreen.main.bounds.width
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        initUI()
    }
    
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func initUI() {
//        bgImage.frame=CGRect(x:0,y:0,width:screen_w,height:64)
//        bgImage.backgroundColor = UIColor(patternImage: UIImage(named:"navbar_bg")!)
//        self.addSubview(bgImage)
        
        //首先创建一个模糊效果
        let blurEffect = UIBlurEffect(style: .dark)
        //接着创建一个承载模糊效果的视图
        let blurView = UIVisualEffectView(effect: blurEffect)
        //设置模糊视图的大小（全屏）
        blurView.frame.size = CGSize(width: screen_w, height: 64)
        //添加模糊视图到页面view上（模糊视图下方都会有模糊效果）
        blurView.alpha=0.7
        self.addSubview(blurView)
        
        backButton = UIButton(type: .custom)
        backButton.frame = CGRect(x:0 , y:20, width:60, height:44)
        backButton.backgroundColor = UIColor.clear
        backButton.setImage(UIImage(named:"btn_Return"), for: .normal)
        self.addSubview(backButton)
        
        titleLabel.frame=CGRect(x:screen_w/2-100,y:20+44/2-8,width:200,height:18)
        titleLabel.text="Old glass"
        titleLabel.textColor=UIColor.white
        titleLabel.textAlignment = .center
        titleLabel.font = UIFont(name: "Arial", size: 16.0)
        self.addSubview(titleLabel)
    }