swift - 如何在 calayer 出现时让视频暂停

Question

我正在尝试让 calayer 在视频出现时暂停它。无论我将它添加为另一个 calayer 还是动画，我都不知道如何去做。这是我在导出之前添加 calayer 时的代码。因此，当动画发生时，我希望视频在出现时暂停，然后在动画停止后恢复播放。

 let titleLayer = CATextLayer()
    titleLayer.backgroundColor = NSColor.clearColor().CGColor
    titleLayer.string = "Dummy text"
    titleLayer.font = NSFont(name: "Helvetica", size: 28)
    titleLayer.shadowOpacity = 0.5
    titleLayer.alignmentMode = kCAAlignmentCenter
    titleLayer.frame = CGRectMake(0, 50, size.width, size.height / 6)

    let animation: CABasicAnimation = CABasicAnimation(keyPath: "opacity")
    animation.duration = 0
    animation.fromValue = Int(1.0)
    animation.toValue = Int(0.0)
    animation.beginTime = 5
    animation.removedOnCompletion = false
    animation.fillMode = kCAFillModeForwards
    titleLayer.addAnimation(animation, forKey: "animateOpacity")

Answer 1

您可以在将动画添加到图层之前暂停视频，然后在动画结束后继续播放。要知道动画何时结束，您可以让一个对象成为 animation 的委托(delegate)，然后在 animationDidStop:finished: 委托(delegate)方法中恢复播放。

func showTitle() {
    // configure animation { .. }
     animation.delegate = self 
    // pause video
     titleLayer.addAnimation(animation, forKey: "animateOpacity")
}

func animationDidStop(anim: CAAnimation, finished flag: Bool) {
    // play video
}