CALayer 裁剪

Question

我有一个 CALayer 配置如下：

private func setup() {

    guard let theLayer = self.layer as? CAGradientLayer else {
        return;
    }


    theLayer.colors = [UIColor.red.cgColor, UIColor.blue.cgColor] 
    theLayer.locations = [0.0, 1.0]
    theLayer.startPoint = CGPoint(x: 0, y: 0)
    theLayer.endPoint = CGPoint(x: 1, y: 0)
    theLayer.frame = self.bounds

}

我想根据用户输入值（在下面的代码中称为“值”）将其剪辑为矩形。我该怎么做？

override func draw(_ rect: CGRect) {
    // Drawing code
        let frame = CGRect(x: 0, y: 0, width: rect.width, height: rect.height * (1-value))

   // How to clip or mask self.layer to above frame? 
}

Answer 1

将层嵌入到具有适当frame 的容器层中，并将其masksToBounds 属性设置为true。