ios - 如何暂停和恢复 UIView.animateWithDuration

Question

我有一张图片，我在 viewDidAppear 中用这段代码制作了动画:

UIView.animateWithDuration(10.5, delay:0.0, options: [], animations:{
self.myImage.transform = CGAffineTransformMakeTranslation(0.0, 200)
}, completion: nil)

我想在点击 myPauseButton 时暂停动画，如果再次点击则恢复动画。

Answer 1

2 个暂停和恢复动画的函数，我取自 here并转换为 Swift。

func pauseLayer(layer: CALayer) {
    let pausedTime: CFTimeInterval = layer.convertTime(CACurrentMediaTime(), from: nil)
    layer.speed = 0.0
    layer.timeOffset = pausedTime
}

func resumeLayer(layer: CALayer) {
    let pausedTime: CFTimeInterval = layer.timeOffset
    layer.speed = 1.0
    layer.timeOffset = 0.0
    layer.beginTime = 0.0
    let timeSincePause: CFTimeInterval = layer.convertTime(CACurrentMediaTime(), from: nil) - pausedTime
    layer.beginTime = timeSincePause
}

我有一个按钮可以暂停或恢复在 viewDidLoad 中启动的动画:

var pause = false
override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)
    UIView.animate(withDuration: 10.5) {
        self.image.transform = CGAffineTransformMakeTranslation(0.0, 200)
    }
}

@IBAction func changeState() {
    let layer = image.layer
    pause = !pause
    if pause {
        pauseLayer(layer)
    } else {
        resumeLayer(layer)
    }
}