//封装的方法：
    func setCornersRadius(_ view: UIView!, radius: CGFloat, roundingCorners: UIRectCorner) {
    
    
        if view == nil {
    
    
            return
        }
        let maskPath = UIBezierPath(roundedRect: view.bounds, byRoundingCorners: roundingCorners, cornerRadii: CGSize(width: radius, height: radius))
        let maskLayer = CAShapeLayer()
        maskLayer.frame = view.bounds
        maskLayer.path = maskPath.cgPath
        maskLayer.shouldRasterize = true
        maskLayer.rasterizationScale = UIScreen.main.scale
        
        view.layer.mask = maskLayer
    }

*-调用方式：
setCornersRadius(contentBtn, radius: 8.0, roundingCorners: [[.topLeft, .bottomLeft]])