在CABasicAnimation(iOS)中跳过
问题描述:
我目前有一个用作视频进度指示器的动画,效果很好。不过,现在我们有一项功能,允许用户通过点击它跳过视频前2.5秒,因此我正在尝试实施进度指示器动画以向动画中跳过2.5秒。我如何将动画向前跳过2.5秒?我试过“animationGroup.timeOffset = 2.5”,但它不起作用。在CABasicAnimation(iOS)中跳过
func performProgressIndicatorAnimation(duration: Float64) {
layer.mask = nil
layer.speed = 1.0
self.duration = duration
let strokeStartAnimation = CABasicAnimation(keyPath: "strokeStart")
strokeStartAnimation.fromValue = 0
strokeStartAnimation.toValue = 1
strokeStartAnimation.duration = duration
strokeStartAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
animationGroup = CAAnimationGroup()
animationGroup.duration = duration
animationGroup.animations = [strokeStartAnimation]
externalCircle.addAnimation(animationGroup, forKey: "animationGroup")
}
//这里是我的externalCircle绘制:
private func drawCircles() {
let externalCirclePath = UIBezierPath(roundedRect: CGRectMake(0, 0, bounds.height, bounds.height), cornerRadius: bounds.height/2)
externalCircle.path = externalCirclePath.CGPath
externalCircle.fillColor = UIColor.clearColor().CGColor
externalCircle.strokeColor = UIColor.whiteColor().CGColor
externalCircle.lineWidth = 2
let internalCircleRadius = bounds.size.height/5
let internalCirclePath = UIBezierPath(roundedRect: CGRectMake(0, 0, internalCircleRadius * 2, internalCircleRadius * 2), cornerRadius: internalCircleRadius)
internalCircle.path = internalCirclePath.CGPath
internalCircle.fillColor = UIColor.whiteColor().CGColor
internalCircle.position = CGPointMake(CGRectGetMidX(bounds) - internalCircleRadius,
CGRectGetMidY(bounds) - internalCircleRadius);
layer.addSublayer(internalCircle)
layer.addSublayer(externalCircle)
}
答
被删除以前的动画,并基于过去(与跳跃)的百分比
func skipProgressIndicatorAnimation(currentTime: CMTime, timeToSkip: Double, duration: CMTime) {
animationGroup = nil
externalCircle.removeAllAnimations()
let percentageElapsedWithSkip = (CMTimeGetSeconds(currentTime) + timeToSkip)/CMTimeGetSeconds(duration)
let strokeStartAnimation = CABasicAnimation(keyPath: "strokeStart")
strokeStartAnimation.fromValue = percentageElapsedWithSkip
strokeStartAnimation.toValue = 1
strokeStartAnimation.duration = CMTimeGetSeconds(duration) - CMTimeGetSeconds(currentTime) - timeToSkip
strokeStartAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
animationGroup = CAAnimationGroup()
animationGroup.duration = CMTimeGetSeconds(duration) - CMTimeGetSeconds(currentTime) - timeToSkip
animationGroup.animations = [strokeStartAnimation]
externalCircle.addAnimation(animationGroup, forKey: "animationGroup")
}
答
启动它这篇如果您使用timeOffset跳过一部分动画,它仍将在相同的总时间内播放。动画只是循环播放,并再次播放,直到它最初开始的地步。 例如:动画:A-> B-> C。如果你使用timeOffSet为了从B开始,它将是:B-> C-> A
在这种情况下,我认为你可能会放弃这个动画,然后添加一个新的动画。
是的,这就是我不得不做的(见我的答案) –