对层冻结感到困惑

Question

我创建了图层动画组（CAAnimation group）。

group.animations = [
        anim1(customUnderlyingLayer: customUnderlyingLayer, semiEllipse: semiEllipse, duration: 0.1,timingCurve: CAMediaTimingFunction(controlPoints: 0, 1.64, 1, 1)),
        anim2(customUnderlyingLayer: customUnderlyingLayer, semiEllipse: semiEllipse, duration: 0.1,timingCurve: LINEAR),
        anim3(customUnderlyingLayer: customUnderlyingLayer, semiEllipse: semiEllipse, duration: 0.1,timingCurve: LINEAR)
         ]
    group.duration = 1

func anim1(customUnderlyingLayer: CustomUnderlyingLayer, semiEllipse: CAShapeLayer,duration: CFTimeInterval,timingCurve :CAMediaTimingFunction ) -> CABasicAnimation {
    // capture the start and end values
    let startValue = customUnderlyingLayer.path1().cgPath
    let endValue = customUnderlyingLayer.path2().cgPath
    
    semiEllipse.path = endValue
    // construct the explicit animation
    let anim = CABasicAnimation(keyPath:#keyPath(CAShapeLayer.path))
    anim.duration = duration
    anim.beginTime = 0
    anim.timingFunction = timingCurve
    anim.fromValue = startValue
    anim.toValue = endValue
    //semiEllipse.add(anim, forKey: nil)
    return anim
}

func anim2(customUnderlyingLayer: CustomUnderlyingLayer, semiEllipse: CAShapeLayer, duration: CFTimeInterval, timingCurve: CAMediaTimingFunction) -> CABasicAnimation{
    // capture the start and end values
    let startValue = customUnderlyingLayer.path2().cgPath
    let endValue = customUnderlyingLayer.path3().cgPath

    semiEllipse.path = endValue
    // construct the explicit animation
    let anim = CABasicAnimation(keyPath:#keyPath(CAShapeLayer.path))
    anim.duration = duration
     let timingCurve = timingCurve
    anim.timingFunction = timingCurve
    anim.fromValue = startValue
    anim.toValue = endValue
    //semiEllipse.add(anim, forKey: nil)
    return anim
}
  func anim3(customUnderlyingLayer: CustomUnderlyingLayer, semiEllipse: CAShapeLayer, duration: CFTimeInterval, timingCurve: CAMediaTimingFunction) -> CABasicAnimation{
    // capture the start and end values
    let startValue = customUnderlyingLayer.path3().cgPath
    let endValue = customUnderlyingLayer.path4().cgPath

  //  semiEllipse.path = endValue
    // construct the explicit animation
    let anim = CABasicAnimation(keyPath:#keyPath(CAShapeLayer.path))
    anim.duration = duration
     let timingCurve = timingCurve
    anim.timingFunction = timingCurve
    anim.fromValue = startValue
    anim.toValue = endValue
    //semiEllipse.add(anim, forKey: nil)
    return anim
}

然后我将图层计时器偏移和速度设置为 0。

semiEllipse.speed = 0
semiEllipse.timeOffset = 0

将动画组添加到 calayer。

 semiEllipse.add(group, forKey: "key")

然后我设置初始时间偏移

   delay(0) {
        self.semiEllipse.timeOffset = 1
    }

我的问题是：

• 当我放入 group.animations 属性 2 动画（anim1 和 anim2）时，一切正常。当我通过滚动视图更改 timeOffset 值时，动画组从 anim1 起始值更改为 anim2 endValue。 但是当我放置 anim3 并通过滚动视图对 timeOffset 属性执行相同的操作时，动画组会将路径从 anim2 startValue 更改为 anim3 endValue。为什么不从 anim1 startValue？？？

Answer 1

在每个 CAAnimation 的 CAAnimationGroup.animations 中，我必须指定 beginTime 值。然后就可以了。