当其框架与UIView相交时，反向UIlabel文本颜色 [英] Inverse UIlabel text color when its frame intersects an UIView

问题描述

嗨我试图在标签rect与UIView相交的情况下改变UILabel的文本颜色，我想也许有一个属性或我可以使用的东西。如下图所示：

Hi Im trying to change the text color of a UILabel in the case when the labels rect intersects an UIView, i was thinking maybe there is a property or something i can use. Like in the image below:

以前是否有人遇到过此问题，或者我应该阅读什么才能开始做这件事？

Did someone meet this issue before, or what should i read to start doing this thing ?

谢谢提前

推荐答案

好难题！这就是我要做的事情：

Good puzzle! Here's what I would do:

1. 两个UIViews。我们将一个称为背景，另一个称为progressBar。 progressBar在其常见的 superview 上堆叠在背景之上，具有相同的 origin 。


2. 他们两者都有一个UILabel作为子视图，两个标签相对于其父级具有相同的来源。 background有一个深色的 backgroundColor ，而且它的标签有浅 textColor ，进度视图还有相反的东西。


3. progressBar的帧宽比背景窄，并且 clipsToBounds == YES

1. Two UIViews. Let's call one the background and the other the progressBar. progressBar is stacked on top of background with the same origin on their common superview.
2. They both have a UILabel as subview, and both labels at the same origin relative to their parent. background has a dark backgroundColor and it's label has light textColor and the progress view has things the other way around.
3. progressBar has a narrower frame width than background and has clipsToBounds==YES

诀窍是，视图的起源相同，标签的起源相同，而顶视图中的clipsToBounds，一切看起来都是正确的。

The trick is, with the views' origins the same and the labels' origins the same, and clipsToBounds on the top view, everything is going to look right.

将这两个视图放入一个名为ReallyCoolProgressView的新UIView子类中，并给它一个公共方法：

Drop those two views into a new UIView subclass called ReallyCoolProgressView, and give it one public method:

- （void ）setProgress :( float）progress progress是一个从0.0到1.0的数字。该方法缩放progressBar宽度并设置两者标签的文本 @Progress％f，进度* 100

-(void)setProgress:(float)progress progress is a number from 0.0 to 1.0. The method scales the progressBar width and sets both label's text @"Progress %f", progress*100

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