drawRect在突出显示时未调用自定义UIButton子类 [英] drawRect not called for custom UIButton subclass when highlighted

问题描述

当使用drawRect作为自定义UIButton子类时，似乎永远不会在突出显示时调用它来绘制按钮。我是否需要在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，没有直截了当UIButton子类化的方法。

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

UIButton不是初始值设定项返回的实际类类型。 UIButton是一系列私人课程的前沿。

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为UIRoundedRectButton。问题是你需要扩展UIRoundedRectButton。这是不可能的，因为它是一个只返回给UIButton的私人类。

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，所有这些类都是私有的。

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.

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