移动时淡入和淡出 UIView [英] Fade in and fade out a UIView while it is moving

问题描述

动画视图很容易:

[UIView animateWithDuration:1.0
                     animations:^{theView.center = newCenter; theView.alpha = 0;}
                     completion:^(BOOL finished){
                         [theView removeFromSuperview];
                     }];

问题是，当我将其添加为子视图时，我希望它淡入并看起来像是在移动.现在它立即出现，然后移动并淡出.

The problem is that when I add it as a subview, I want it to fade in and already look like it is moving. Right now it appears immediately, then moves and fades out.

所以，我需要将它的初始 alpha 设置为零，在移动时快速淡入淡出，然后淡出.UIView 动画可以做到这一点吗?我不能让两个相互竞争的动画块在同一个对象上工作，对吗?

So, I need to set it's initial alpha to zero, fade it quickly while it is moving, then fade it out. Is this possible with UIView animations? I can't have two competing animation blocks working on the same object right?

推荐答案

您需要做的就是连续应用 2 个动画.像这样的东西::

All you need to do is apply 2 animations back-to-back. Something like this ::

theView.alpha = 0;
[UIView animateWithDuration:1.0
                 animations:^{
                     theView.center = midCenter;
                     theView.alpha = 1;
                 }
                 completion:^(BOOL finished){
                     [UIView animateWithDuration:1.0
                                      animations:^{
                                          theView.center = endCenter;
                                          theView.alpha = 0;
                                      }
                                      completion:^(BOOL finished){
                                          [theView removeFromSuperview];
                                      }];
                 }];

所以在第一秒它会在移动时出现，然后在下一秒它会淡出

So in the 1st second it will appear while moving and then in the next second it will fade out

希望能帮到你

这篇关于移动时淡入和淡出 UIView的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！