UIView设置圆角

let maskPath = UIBezierPath.init(roundedRect: self.bounds, byRoundingCorners: UIRectCorner(rawValue: UIRectCorner.topLeft.rawValue | UIRectCorner.topRight.rawValue), cornerRadii: CGSize.init(width: 50
        , height:50))
    
    let maskLayer = CAShapeLayer.init()
    maskLayer.frame = self.bounds
    maskLayer.path = maskPath.cgPath
    self.layer.mask = maskLayer
    backView.layer.backgroundColor = UIColor.clear.cgColor