如何在 UIButton 子类中覆盖 -drawrect? [英] How to override -drawrect in UIButton subclass?

问题描述

HI. I need to write some text over a custom button. So I subclassed UIButton. In -drawrect, I write the text I need. The problem is that the text ends up under the button. After I write my text, UIButton's drawrect goes ahead and draws on top of me.

I am not even calling [super drawrect: rect] even though I was anticipating calling it before I did my drawing. It seems that UIButton's drawrect will get called regardless.

Any ideas? Thanks.

解决方案

As other people have said, you don't need to subclass UIButton - infact it's best not to as UIButton is pretty complex (as you found). You have three options:

• Leave the button's title blank and add a new text field to the button at the position you want.
• if you are using 3.0 access the button's label property. Although the label itself is read only its properties (including frame) are not.
• Sub-class UIControl. UIControl is a UIView so you can add other views - text and images and it is UIView that implements the action message behaviour (addTarget:action:forControlEvents:). UIButton implements statefulness on top of this.

If you don't need things like UIButton's setTitle:forState: and associated functionality but you are using a lot of these controls I would use the third option. Otherwise use the first (or second if you are on 3.0).

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