将动画添加到子视图时立即调用 CATransaction 完成块

Posted 2023-03-13

【中文标题】将动画添加到子视图时立即调用 CATransaction 完成块

【英文标题】：CATransaction completion block being called immediately when animation is added to subview

【发布时间】：2019-03-08 23:01:00

【问题描述】：

我正在尝试在新添加的 UIImageView 作为子视图上启动动画，但似乎在这种情况下会立即调用完成块，即使在 CATransaction.setCompletionBlock 之后添加了动画

addSubview(imageView)

CATransaction.begin()

let posAnimation = positionAnimation(startPoint: startPoint, endPoint: endPoint, beginTime: beginTime, duration: duration)
let alpAnimation = alphaAnimation(beginTime: beginTime, duration: duration)

CATransaction.setCompletionBlock [weak self] in
print("deleting view")
//imageView.removeFromSuperview()


imageView.layer.add(posAnimation, forKey: nil)
imageView.layer.add(alpAnimation, forKey: nil)

CATransaction.commit()

动画：

private func positionAnimation(startPoint: CGPoint, endPoint:CGPoint, beginTime: CFTimeInterval, duration: CFTimeInterval) -> CAKeyframeAnimation 
    let positionAnimation = CAKeyframeAnimation(keyPath: "position")

    positionAnimation.path = customPath(middlePoint: startPoint, endPoint: endPoint).cgPath
    positionAnimation.isRemovedOnCompletion = false
    positionAnimation.duration = duration
    positionAnimation.beginTime = beginTime
    positionAnimation.fillMode = CAMediaTimingFillMode.forwards
    return positionAnimation


private func alphaAnimation(beginTime: CFTimeInterval, duration: CFTimeInterval) -> CAKeyframeAnimation 
    let alphaAnimation = CAKeyframeAnimation(keyPath: "opacity")
    alphaAnimation.isRemovedOnCompletion = false
    alphaAnimation.fillMode = CAMediaTimingFillMode.forwards
    alphaAnimation.values = [1.0, 1.0, 0.0]
    alphaAnimation.keyTimes = [0.0,0.5,1.0]
    alphaAnimation.duration = duration
    alphaAnimation.beginTime = beginTime
    return alphaAnimation

知道为什么它不起作用吗？

【问题讨论】：

beginTime和duration的值是多少？

持续时间 = 1 和 beginTime = CACurrentMediaTime() + 1

【参考方案1】：

很明显，动画不在渲染树上。即视图没有superView。或者它的superView 没有superView。您可能需要检查视图实现功能是否已添加到 window 或 view 某处。

【讨论】：

在viewDidLoad() 之后很久，我将imageView 直接添加到UIViewController 的view 中

所以视图是 UIView 的自定义子类？这个视图的类型是什么，你在哪里实现 addSubView(imageView)