突出显示时不为自定义 UIButton 子类调用 drawRect [英] drawRect not called for custom UIButton subclass when highlighted

问题描述

当为自定义 UIButton 子类使用 drawRect 时，它似乎永远不会在突出显示时被调用来绘制按钮.我是否需要在我的触摸事件中为我的按钮调用 setNeedsDisplay?

When using drawRect for a custom UIButton subclass, it never seems to get called to draw the button when highlighted. Do I need to call setNeedsDisplay for my button in my touch events?

推荐答案

据我所知，没有直接的方法可以继承 UIButton.

As far as i can tell there is no straight forward way to subclass UIButton.

UIButton 不是初始化器返回的实际类类型.UIButton 是一系列私有类的前端.

UIButton is not the actual class type that is returned by the initializers. UIButton is kind of a front for a series of private classes.

说你有:

UIButton *myButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
NSLog(@"myButton type: %@", [myButton description]);

您会发现日志中返回的类型是UIRoundedRectButton".问题是您需要扩展UIRoundedRectButton".这是不可能的，因为它是一个只返回给 UIButton 的私有类.

You will find the type returned in the log to be "UIRoundedRectButton". The problem with that is you would need to have extended "UIRoundedRectButton". That is not possible as it is a private class which is only ever returned to UIButton.

除此之外，UIRoundedRectButton"不是唯一可能返回的类，所有这些都是私有的.

On top of that "UIRoundedRectButton" is not the only possible returned class all of which are private.

换句话说，UIButton 的构建方式不适合扩展.

In other words UIButton was built in manner that is not suited to be extended.

这篇关于突出显示时不为自定义 UIButton 子类调用 drawRect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！