ios - 如何在其蒙版周围绘制 CALayer 边框？

Question

所以，我有一个 CALayer，它有一个 mask ，我想在这个图层的 mask 周围添加边框。例如，我已经为图层设置了三角形蒙版，我想在该图层周围设置边框。

谁能帮我解决这个问题？

Answer 1

swift 4

class CustomView: UIView {
override func draw(_ rect: CGRect) {
    super.draw(rect)
    self.backgroundColor = UIColor.black

    //setup path for mask and border
    let halfHeight = self.bounds.height * 0.5
    let maskPath = UIBezierPath(roundedRect: self.bounds,
                                byRoundingCorners: [.topLeft, .bottomRight],
                                cornerRadii: CGSize(width: halfHeight,
                                                    height: halfHeight))

    //setup MASK
    self.layer.mask = nil;
    let maskLayer = CAShapeLayer()
    maskLayer.frame = self.bounds;
    maskLayer.path = maskPath.cgPath
    self.layer.mask = maskLayer

    //setup Border for Mask
    let borderLayer = CAShapeLayer()
    borderLayer.path = maskPath.cgPath
    borderLayer.lineWidth = 25
    borderLayer.strokeColor = UIColor.red.cgColor
    borderLayer.fillColor = UIColor.clear.cgColor
    borderLayer.frame = self.bounds
    self.layer.addSublayer(borderLayer)
}