动画块复位到原来的位置更新后的文本 [英] Animation Blocks resets to original position after updating text

问题描述

我目前正在测试我的应用程序的IOS 8.释放我发现后，我完成一个动画块，动画重置如果我更新任何标签的文本。我跑用下面所示的一种方法的简单例子。运行这个例子的结果是以下内容：

• 单击则myButton 第一时间动画运行，但是当复位标签文本被更改。


• 单击则myButton 第二次 - 动画运行，但不会恢复到原来的位置。

看起来这是因为标签文本不会更改。如果我完全删除该行更新文本，这也从末停止重置动画。

我想解决这个问题，这样的方法运行时，标签文字可以无需重新设置动画更新。

   - （IBAction为）移动：（ID）发送{[UIView的animateWithDuration：0.4延时：0.0
                 选项​​：UIViewAnimationOptionBeginFromCurrentState
                 动画：^ {
                     self.myButton.center = CGPointMake（200,300）;
                 }完成：^（BOOL完）{                     如果（成品）{
                         self.myLabel.text = @感动;
                     }                 }];
}
 

解决方案

这问题可以通过让自动布局上的UIView设置造成的。严格地说，如果您正在使用自动布局，那么你不应该有生命物体的绝对位置 - 你应该动画它们的约束，而不是。

更改标签文本，一旦你的动画正在进行触发布局更新，而iOS洗牌周围的一切都符合原来的视图约束。 （我怀疑这是从iOS7行为上的改变）。

快速修复：取消选中自动布局上来看，这应该按预期工作

I'm currently testing my apps for the release of IOS 8. I noticed that after I performed an animation block, the animation resets if I update the text of any label. I ran a simple example with one method shown below. Running this example results in the following:

• Clicking myButton the first time- animation runs but resets when the label text is changed.
• Clicking myButton the second time - animation runs but does not reset to original position.

It seems like this happens because the label text doesn't change. If I completely remove the line updating the text, this also stops the animation from resetting at the end.

I would like to fix this so that when the method runs, the label text can be updated without resetting the animation.

- (IBAction)move:(id)sender {

[UIView animateWithDuration:0.4 delay:0.0
                 options:UIViewAnimationOptionBeginFromCurrentState
                 animations:^{
                     self.myButton.center = CGPointMake(200, 300);
                 }completion:^(BOOL finished){

                     if(finished){
                         self.myLabel.text=@"moved";
                     }

                 }];
}

解决方案

This problem can be caused by having Auto Layout set on the UIView. Strictly speaking, if you're using Auto Layout, then you shouldn't animate the absolute position of objects -- you should animate their constraints instead.

Changing the label text once your animation is underway triggers a layout refresh, and iOS shuffles everything around to comply with the original view constraints. (I suspect this is a behavioural change from iOS7).

Quick fix: un-check Auto Layout on the View, and this should work as expected.

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