ios - 如何使用贝塞尔路径为对象设置动画？

Question

这是我绘制虚线的代码

func drawLine() {

    let shapeLayer = CAShapeLayer()
    shapeLayer.bounds = viewDraw.bounds
    shapeLayer.position = CGPoint(x: viewDraw.bounds.width/2, y: viewDraw.bounds.height/2)
    shapeLayer.fillColor = nil
    shapeLayer.strokeColor = ColorConstants.ThemeColor.cgColor
    shapeLayer.lineWidth = 3
    shapeLayer.lineJoin = CAShapeLayerLineJoin.round // Updated in swift 4.2
    shapeLayer.lineDashPattern = [10]

    let path = UIBezierPath(roundedRect: viewDraw.bounds, cornerRadius: viewDraw.bounds.size.height/2)
    shapeLayer.path = path.cgPath

    viewDraw.layer.addSublayer(shapeLayer)

    let animation = CABasicAnimation(keyPath: "strokeEnd")
    animation.fromValue = 0
    animation.duration = 1
    shapeLayer.add(animation, forKey: "MyAnimation")
}

现在，根据我的屏幕截图，我想在虚线无限时间内将蓝点动画化为红点。当蓝点到达红点时，它将以蓝点点重新开始。

注意:整个屏幕是动态的，根据屏幕高度画线也是动态的

任何帮助将不胜感激

Answer 1

你快到了

现在您必须使用具有属性 path 的 CAKeyframeAnimation 添加动画，您可以在其中传递要设置动画的路径

这里是工作示例代码

func drawLine() {

    let shapeLayer = CAShapeLayer()
    shapeLayer.bounds = self.view.bounds
    shapeLayer.position = CGPoint(x: self.view.bounds.width/2, y: self.view.bounds.height/2)
    shapeLayer.fillColor = nil
    shapeLayer.strokeColor = UIColor.red.cgColor
    shapeLayer.lineWidth = 3
    shapeLayer.lineJoin = CAShapeLayerLineJoin.round // Updated in swift 4.2
    shapeLayer.lineDashPattern = [10]

    let path = UIBezierPath(roundedRect: self.view.bounds, cornerRadius: self.view.bounds.size.height/2)
    shapeLayer.path = path.cgPath

    self.view.layer.addSublayer(shapeLayer)

    let animation1 = CABasicAnimation(keyPath: "strokeEnd")
    animation1.fromValue = 0
    animation1.duration = 1
    shapeLayer.add(animation1, forKey: "MyAnimation")

    // Create  squareView and add animation 
    let animation = CAKeyframeAnimation(keyPath: #keyPath(CALayer.position))
    animation.duration = 1
    animation.repeatCount = MAXFLOAT
    animation.path = path.cgPath

    let squareView = UIView()

   // Don't worry about x,y and width and height it will not affect the animation 
    squareView.frame = CGRect(x: 0, y: 0, width: 50, height: 50)
    squareView.backgroundColor = .lightGray
    view.addSubview(squareView)
    // You can also pass any unique string value for key
    squareView.layer.add(animation, forKey: nil)

}

您可以查看本教程以获得更多帮助http://mathewsanders.com/animations-in-swift-part-two/