在CABasicAnimation（iOS）中跳過

我目前有一個用作視頻進度指示器的動畫，效果很好。不過，現在我們有一項功能，允許用戶通過點擊它跳過視頻前2.5秒，因此我正在嘗試實施進度指示器動畫以向動畫中跳過2.5秒。我如何將動畫向前跳過2.5秒？我試過「animationGroup.timeOffset = 2.5」，但它不起作用。在CABasicAnimation（iOS）中跳過

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") 

}

//這裏是我的externalCircle繪製：

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) 
}

來源

2016-07-29 Josh O' Connor

被刪除以前的動畫，並基於過去（與跳躍）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") 

}

來源

2016-07-29 17:59:36

啓動它這篇如果您使用timeOffset跳過一部分動畫，它仍將在相同的總時間內播放。動畫只是循環播放，並再次播放，直到它最初開始的地步。例如：動畫：A-> B-> C。如果你使用timeOffSet爲了從B開始，它將是：B-> C-> A

在這種情況下，我認爲你可能會放棄這個動畫，然後添加一個新的動畫。

來源

2016-07-29 18:03:47 nghiahoang

是的，這就是我不得不做的（見我的答案） –

在CABasicAnimation（iOS）中跳過

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