ios - 清除 CAShapeLayer 中的所有内容

Question

我有一个在 AVCaptureVideoPreviewLayer 顶部绘制矩形的函数。这个矩形需要在触发时刷新，并绘制一个新的矩形。最好是从 CAShapeLayer 中删除所有内容，还是只删除该层并添加一个新层？我也不知道该怎么做，但我的尝试如下。

func showRectangle(recLayer: CAShapeLayer, vnRectangleObservation: VNRectangleObservation) -> Void{

    // new CAShapeLayer
    let newLayer = CAShapeLayer.init()

    let rectangle = UIBezierPath.init()
    rectangle.move(to: CGPoint.init(x: vnRectangleObservation.topLeft.x, y: vnRectangleObservation.topLeft.y))
    rectangle.addLine(to: CGPoint.init(x: vnRectangleObservation.topRight.x, y: vnRectangleObservation.topRight.y))
    rectangle.addLine(to: CGPoint.init(x: vnRectangleObservation.bottomRight.x, y: vnRectangleObservation.bottomRight.y))
    rectangle.addLine(to: CGPoint.init(x: vnRectangleObservation.bottomLeft.x, y: vnRectangleObservation.bottomLeft.y))

    rectangle.close()

    newLayer.opacity = 0.4
    newLayer.path = rectangle.cgPath
    newLayer.fillColor = UIColor.orange.cgColor

    // replace current layer containing old rectangle
    recLayer.replaceSublayer(recLayer, with: newLayer)

}

Answer 1

您可以遍历所有子层并删除它们。

for sublayer in yourLayer.sublayers ?? [] {
    sublayer.removeFromSuperlayer()
}

只需使用 addSublayer 添加新的:

let newSublayer = CAShapeLayer()
yourLayer.addSublayer(newSublayer)