ios - 当动画添加到 subview 时立即调用 CATransaction 完成 block

Question

我试图在新添加的 UIImageView 作为 subview 上启动动画，但在这种情况下似乎会立即调用完成 block ，即使动画是在 CATransaction.setCompletionBlock 之后添加的

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？

Answer 1

显然，动画不在渲染树上。即 View 没有 superView。或其 superView 的某个地方没有 superView。您可能需要检查 View 实现函数是否已添加到 window 或 view 某处。