Swift 3 动画:代码运行但没有视觉效果

Question

我的动画代码被执行(我可以使用任何动画行上的断点停止执行(，但我在视觉上什么也看不到。它甚至需要我为无所事事的持续时间设置的一秒钟，它只是执行下一个 segue。我的文本字段应该在 1 秒内淡出。

        //animate text fields (fade till dissappear)
        let animationTextFields = {() -> Void in
            self.firstField.alpha = 0.0
            self.secondField.alpha = 0.0
            self.thirdField.alpha = 0.0
            self.fourthField.alpha = 0.0
        }

        UIView.animate(withDuration: 1.0, animations: animationTextFields)

        //animate next button (flies right)
        //animate back button (flies left)
        //animate "please" label (flies up)


        self.performSegue (withIdentifier: "SegueToMainNavigation", sender: self)

如您所见，我还需要进一步的动画，但一次一个步骤。

知道为什么我的动画没有发生吗？

Answer 1

在动画完成后放置 segue。

  UIView.animate(withDuration: 1.0, delay: 0.0, options: [], animations: animationTextFields, completion: { (finished: Bool) in
            self.performSegue (withIdentifier: "SegueToMainNavigation", sender: self)
    })

Answer 2

如果您希望它们同时发生，您可以通过以下transitionCoordinator协调动画与过渡：

performSegue(withIdentifier: "SegueIdentifier", sender: self)
transitionCoordinator?.animate(alongsideTransition: { context in
    UIView.animate(withDuration: 1) {
        self.label.alpha = 0         // fade out
    }
}, completion: { context in
    self.label.alpha = 1             // if you want, when done, make it visible again so when you return back here you can see it
})

Answer 3

尝试在

闭包animationTextFields内编写self.layoutIfNeeded()。

Answer 4

试试这段代码

UIView.animate(withDuration: 0.3)
{
 self.performSegue (withIdentifier: "SegueToMainNavigation", sender: self)          
}