我在这里找到了很多解决方案,但不是Swift,我知道你可以用UIImageView做到这一点,但在我的情况下,我需要以编程方式为UIButton设置alpha透明背景图像。最好的是UIImage扩展!
let img = UIImage(named: "imageWithoutAlpha")
var imgInsets = UIEdgeInsetsMake(0, 24, 0, 24)
image = image!.resizableImageWithCapInsets(imgInsets)
let myButton = UIButton(frame: CGRect(x: 50, y: 50, width: img!.size.width, height: img!.size.height))
myButton.setBackgroundImage(img, forState: UIControlState.Normal)
myButton.contentEdgeInsets = UIEdgeInsetsMake(0, 20, 0, 20)
myButton.setTitle("Startbutton", forState: UIControlState.Normal)
myButton.setTitleColor(UIColor.blackColor(), forState: UIControlState.Normal)
myButton.sizeToFit()
view.addSubview(myButton)
目前的结果:
期望的结果:
幸运的是,我能够帮助自己,并希望与您分享我的解决方案:
斯威夫特3
// UIImage+Alpha.swift
extension UIImage {
func alpha(_ value:CGFloat) -> UIImage {
UIGraphicsBeginImageContextWithOptions(size, false, scale)
draw(at: CGPoint.zero, blendMode: .normal, alpha: value)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
}
我添加到我的项目中的上述新的Swift扩展,然后我更改了UIButton示例如下,以获得透明度为50%的alpha透明背景图像。
let img = UIImage(named: "imageWithoutAlpha")!.alpha(0.5)
let myButton = UIButton()
myButton.setBackgroundImage(img, for: .normal)
最简单的方法是将你的UIImage
放入UIImageView
并在那里设置alpha。
let image = UIImage(named: "imageWithoutAlpha")
let imageView = UIImageView(image: image)
imageView.alpha = 0.5
myButton.setBackgroundImage(image, forState: UIControlState.Normal)
我能够使用以下代码设置alpha:
self.imageView.image = UIImageView(image: "image.png")
imageView.alpha = 0.5