在执行代码之前等待 Swift 动画完成 [英] Wait for Swift animation to complete before executing code

问题描述

我正在尝试为 UIImageView 设置动画，然后在动画完成后隐藏图像视图.但是，在动画完成之前，图像视图会被隐藏.我查看了类似的问题，他们建议在完成后实现动画侦听器或在动画代码中执行 .hidden 代码，但是我不确定如何在下面的shakeView() 函数中影响它.

I am trying to animate a UIImageView and then hide the image view after animation is complete. However the imageview gets hidden before the animation is completed. I looked at similar questions and they recommend implementing an animation listener or executing the .hidden code within the animation code upon completion however I'm not sure how to affect this within the shakeView() function below.

如何在动画完成后才显示抖动动画并隐藏图像视图?

How do I show the shake animation and hide the image view only after the animation is complete?

使用以下代码调用动画:

Animation is called using the following code:

shakeView(image1!)
shakeView(image2)
image1!.hidden = true
image2.hidden = true

动画函数本身看起来像这样:

The animation function itself looks like this:

func shakeView(iv: UIImageView){
    var shake:CABasicAnimation = CABasicAnimation(keyPath: "position")
    shake.duration = 0.1
    shake.repeatCount = 2
    shake.autoreverses = true

    var from_point:CGPoint = CGPointMake(iv.center.x - 5, iv.center.y)
    var from_value:NSValue = NSValue(CGPoint: from_point)

    var to_point:CGPoint = CGPointMake(iv.center.x + 5, iv.center.y)
    var to_value:NSValue = NSValue(CGPoint: to_point)

    shake.fromValue = from_value
    shake.toValue = to_value
    iv.layer.addAnimation(shake, forKey: "position")
}

推荐答案

您可以使用 CATransaction 在动画完成后调用完成块.

You can use a CATransaction to call a completion block after the animation completes.

func shakeView(iv: UIImageView){

    CATransaction.begin()
    CATransaction.setCompletionBlock({
        iv.hidden = true
    })
    var shake:CABasicAnimation = CABasicAnimation(keyPath: "position")
    shake.duration = 0.1
    shake.repeatCount = 21
    shake.autoreverses = true

    var from_point:CGPoint = CGPointMake(iv.center.x - 5, iv.center.y)
    var from_value:NSValue = NSValue(CGPoint: from_point)

    var to_point:CGPoint = CGPointMake(iv.center.x + 5, iv.center.y)
    var to_value:NSValue = NSValue(CGPoint: to_point)

    shake.fromValue = from_value
    shake.toValue = to_value
    iv.layer.addAnimation(shake, forKey: "position")
    CATransaction.commit()
}

或者您也可以将两个动画组合在 CATransaction 中，如下所示.

Or you can also group both animations together in a CATransaction as follows.

func shakeView(iv: UIImageView){
    var shake:CABasicAnimation = CABasicAnimation(keyPath: "position")
    shake.duration = 0.1
    shake.repeatCount = 21
    shake.autoreverses = true

    var from_point:CGPoint = CGPointMake(iv.center.x - 5, iv.center.y)
    var from_value:NSValue = NSValue(CGPoint: from_point)

    var to_point:CGPoint = CGPointMake(iv.center.x + 5, iv.center.y)
    var to_value:NSValue = NSValue(CGPoint: to_point)

    shake.fromValue = from_value
    shake.toValue = to_value
    iv.layer.addAnimation(shake, forKey: "position")
}

override func viewDidLoad() {
    CATransaction.begin()

    CATransaction.setCompletionBlock({
        self.image1.hidden = true
        self.image2.hidden = true
    })
    shakeView(image1)
    shakeView(image)
  CATransaction.commit()
}

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