同时运行两个动画

Question

我正在尝试使用两个视图创建动画，但在执行它们时遇到了一些意外行为。

我想在做第二个动画时为两个视图位置设置动画 transitionFlipFromBottom

这是代码：

let initialFrame = CGRect(x: xpos, y: -310, width: 300, height: 300)

let firstView = UIView()
firstView.backgroundColor = .red
firstView.frame = initialFrame

let secondView = UIView()
secondView.backgroundColor = .white
secondView.frame = initialFrame
secondView.isHidden = false


self.view.addSubview(firstView)
self.view.addSubview(secondView)


// Here I try to move the views on screen while fliping them
UIView.animate(withDuration: 1, delay: 0, options: .curveEaseOut, animations: {
    secondView.center = self.view.center
    firstView.center = self.view.center
    self.flip(firstView: firstView, secondView: secondView)
}, completion: nil)



// This function flips the views vertically while it animates the transition from the first to the second view
fileprivate func flip(firstView: UIView, secondView: UIView) {
    let transitionOptions: UIViewAnimationOptions = [.transitionFlipFromBottom, .showHideTransitionViews]
    UIView.transition(with: firstView, duration: 0.5, options: transitionOptions, animations: {
        firstView.isHidden = true
    })

    UIView.transition(with: secondView, duration: 0.5, options: transitionOptions, animations: {
        secondView.isHidden = false
    })
}

上面的代码无法同时执行两个动画。

只有在第一个动画（移动帧）完成后，我将flip函数调用放置在completion块内，它才有效，如下所示：

UIView.animate(withDuration: 1, delay: 0, options: .curveEaseOut, animations: {
    secondView.center = self.view.center
    firstView.center = self.view.center
}, completion: {(_) in
    self.flip(firstView: dummyView, secondView: newGroupView)
})

我什至尝试使用，UIView.animateKeyframes但它仍然不起作用。

我在这里错过了什么吗？

谢谢你。

Answer 1

有几件事：

1. 在 中transition，指定.allowAnimatedContent选项。

2. 推迟动画：

   DispatchQueue.main.async {
       UIView.animate(withDuration: 1, delay: 0, options: [.curveEaseOut], animations: {
           secondView.center = CGPoint(x: self.view.bounds.midX, y: self.view.bounds.midY)
           firstView.center = CGPoint(x: self.view.bounds.midX, y: self.view.bounds.midY)
           self.flip(firstView: firstView, secondView: secondView)
       }, completion: { _ in
       })
   }
   

3. 有点不相关，你不想要：

   secondView.center = self.view.center
   

   相反，请执行以下操作：

   secondView.center = CGPoint(x: self.view.bounds.midX, y: self.view.bounds.midY)
   

   您想要在ofsecondView.center的坐标空间中设置，而不是在s中。boundsviewviewsuperview