swift

1.

extension UIView{
    func addCorner(conrners: UIRectCorner , radius: CGFloat) {
        let maskPath = UIBezierPath(roundedRect: self.bounds, byRoundingCorners: conrners, cornerRadii: CGSize( radius, height: radius))
        let maskLayer = CAShapeLayer()
        maskLayer.frame = self.bounds
        maskLayer.path = maskPath.cgPath
        self.layer.mask = maskLayer
    }
}

2. 使用。 controller 在

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        //指定位置切圆角
        self.bgview.jy.addCorner(conrners: [.topLeft , .topRight], radius: 6)
    }

自定义view 在 draw方法/layoutsubviews里面写 这里面可以获取到frame 进行圆角添加

override func draw(_ rect: CGRect) {
    super.draw(rect)

　　self.bgview.jy.addCorner(conrners: [.topLeft , .topRight], radius: 6)

}

- (void)layoutSubviews
{
    [super layoutSubviews];

　　self.bgview.jy.addCorner(conrners: [.topLeft , .topRight], radius: 6)

}