对在drawRect（）中绘制的贝塞尔曲线路径进行动画处理

问题描述

我有这样的形状，我会画在 drawRect（）

I have this shape that i draw in drawRect()

var rectanglePath = UIBezierPath()

override func drawRect(rect: CGRect) {
    rectanglePath = UIBezierPath(rect: self.bounds)
    rectanglePath.fillWithBlendMode(kCGBlendModeMultiply, alpha: 0.7)
    layer.shouldRasterize = true
}

当 prepareForEditing 函数被调用，我想给矩形路径设置动画。我尝试过

When prepareForEditing function is called, i want to animate the rectanglePath. I tried

  func prepareForEditing(editing:Bool){
        UIView.animateWithDuration(0.5,
            animations: {
              self.rectanglePath = makeNewShape()
            }
       )
  }

什么都没有发生。您能告诉我我的代码有什么问题吗？

Nothing happens. Can you please tell me what's wrong with my code?

推荐答案

要为CGPath设置动画，您不能使用UIView.animation方法。
我创建了自定义UIView子类，以向您展示如何为CGPaths形状制作动画，请参考注释并根据您的要求进行修改：

To animate CGPath you cannot use UIView.animation methods.I created custom UIView subclass to show you how can you animate CGPaths shape, please refer to the comments and amend it for your requirements:

class MyView: UIView {

let shapeLayer = CAShapeLayer()
let maskLayer = CAShapeLayer()
var rectanglePath = UIBezierPath()

override func didMoveToSuperview() {
    super.didMoveToSuperview()

    backgroundColor = UIColor.clear

    // initial shape of the view
    rectanglePath = UIBezierPath(rect: bounds)

    // Create initial shape of the view
    shapeLayer.path = rectanglePath.cgPath
    shapeLayer.strokeColor = UIColor.black.cgColor
    shapeLayer.fillColor = UIColor.clear.cgColor
    layer.addSublayer(shapeLayer)

    //mask layer
    maskLayer.path = shapeLayer.path
    maskLayer.position =  shapeLayer.position
    layer.mask = maskLayer
}

func prepareForEditing(editing:Bool){

    let animation = CABasicAnimation(keyPath: "path")
    animation.duration = 2

    // Your new shape here
    animation.toValue = UIBezierPath(ovalIn: bounds).cgPath
    animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)

    // The next two line preserves the final shape of animation,
    // if you remove it the shape will return to the original shape after the animation finished
    animation.fillMode = kCAFillModeForwards
    animation.isRemovedOnCompletion = false

    shapeLayer.add(animation, forKey: nil)
    maskLayer.add(animation, forKey: nil)
  }
}

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