如何设置 UIButton 背景色的 alpha？

Question

I'm currently making a custom button function but want to be able to set the alpha of the background color. This is what I have so far:

  func roundButtonCornersAndAddBorderColor(button: UIButton) {
    button.backgroundColor = .clear
    button.layer.cornerRadius = 5
    button.layer.borderWidth = 1
    button.layer.borderColor = UIColor.white.cgColor
  }

Answer 1

To set the color with alpha use:

UIColor(red: 0.5, green: 0.5, blue:0, alpha: 1.0)

or:

 button.backgroundColor?.withAlphaComponent(0.5)

Answer 2

在 Swift 5 中将 alpha 设置为 0.5 所需的代码是

button.alpha = 0.5