里面的UILabel UIView的没有动画，使用自动版式 [英] UILabel does not animate inside UIView, autolayouts used

问题描述

我有一个非常简单的应用程序。它包含一个红色的观点和里面一个绿色标签。还存在运行动画的按钮。我通过动画改变其宽度约束常量的值红色的看法。

I have a very simple application. It contains a red view and a green label inside it. There is also a button that runs animation. I animate the red view by changing its width constraint constant's value.

[self.view layoutIfNeeded];
[UIView animateWithDuration:0.4 animations:^{
    self.widthConstraint.constant = width;
    [self.view layoutIfNeeded];
}];

红色视图动画的预期，但绿色标签内立即改变其宽度。我打了不同的动画旗帜，从这么试了提示，但并没有带来它的工作。

The red view animates as expected, but the green label inside changes its width instantly. I played with different animation flags, tried several tips from SO but did not bring it work.

请找到来源这里。

TIA

推荐答案

好像我已经找到了问题的根源。约束是不是一个麻烦，的UILabel 是

It seems like I've found the root of the problem. Constraints are not a trouble, UILabel is.

如果您替换的UILabel 在我的简单的项目的UIView 如预期将顺利动画。这是的UILabel 内容动画的问题。可以达到正确的动画行为设置 label.contentMode = UIViewContentModeCenter ，但它看起来丑陋。

If you replace UILabel in my project with simple UIView it will animate smoothly as expected. It's a question of UILabel content animation. You can reach correct animation behaviour set label.contentMode = UIViewContentModeCenter but it looks ugly.

解决这个问题的最好办法 - 不要尝试动画过程中更改的UILabel 的大小。尝试发明一些其他的行为。在我来说，我换的UILabel 的阿尔法为0，x位置，以大于容器视图的宽度。

The best way to solve this problem - not try to change size of UILabel during animation. Try to invent some other behaviour. In my case I change UILabel's alpha to 0 and x position to greater then container view's width.

请找到的UILabel 动画<更详细信息href=\"http://stackoverflow.com/questions/3298764/animating-uilabel-size-decrease/7923430#7923430\">here.

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