如何在禁用状态下更改 UIButton 图像 alpha?

问题描述

我有一个带有图像的 UIButton，在它的禁用状态下，这个图像应该有 .3 alpha.

I have a UIButton with an image and on its disabled state, this image should have .3 alpha.

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
UIImage *arrowImage = [UIImage imageNamed:@"arrow.png"];
[button setImage:arrowImage forState:UIControlStateNormal];

// The arrow should be half transparent here
[button setImage:arrowImage forState:UIControlStateDisabled];

我该如何做到这一点?

更新:我注意到，默认情况下 UIButton 在禁用状态下会降低图像的 alpha(可能为 0.5?).但我想知道如何微调这个值.

UPDATE: I noticed, by default UIButton does reduce the alpha of the image on disabled state (probably at .5?). But I'd like to know how to fine-tune this value.

推荐答案

如果在禁用按钮时设置 alpha 不起作用，那么只需将禁用的图像设置为所需的 alpha 值.

If setting alpha while the button is disabled doesn't work, then just make your disabled image at the alpha value you desire.

刚刚测试过，你可以在 UIButton 上设置 alpha，不管状态如何，效果都很好.

Just tested this, you can set the alpha on the UIButton, regardless of state and it works just fine.

self.yourButton.alpha = 0.25;

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