无法设置CALayer的边框颜色 [英] Can't set CALayer's border color

问题描述

我正在尝试自定义UIButton的外观，如下所示:

I'm trying to customize the appearance of a UIButton, like this:

@IBOutlet weak var button: UIButton!

override func viewDidLoad() {
    super.viewDidLoad()

    button.layer.cornerRadius = button.frame.size.width / 2
    button.layer.borderColor = UIColor.cyan.cgColor
    button.layer.borderWidth = 1
}

但是，当我运行它时，它仅显示按钮的文字，什么可能导致问题呢?

However when I run it, it displays nothing but the text of the button, what could cause the problem?

推荐答案

问题是您运行此代码的时间过早(在 viewDidLoad 中).您的 cornerRadius 计算取决于 calculateButton.frame ，但目前尚不知道其值.将代码移到 viewDidLayoutSubviews 中，我想您会发现它可以按预期工作.

The problem is that you are running this code too soon (in viewDidLoad). Your cornerRadius calculation depends upon calculateButton.frame, but its value is not known at this time. Move your code into viewDidLayoutSubviews and I think you will find that it works as you expect.

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