How to set the alpha of an UIImage in SWIFT programmatically?

Question

I found a lot solutions here but not for Swift, and I know you can do this with a UIImageView, but in my case i need an programmatically set alpha transparent background image for an UIButton. Best would be an UIImage extension!

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) 

Current result:

Desired result:

Answer 1

Luckily I was able to help myself and would like to share with you my solution:

Swift 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!        } } 

The above new Swift extension I added to my project and then I changed the UIButton example as follows, to have an alpha transparent background image with a transparency of 50%.

let img = UIImage(named: "imageWithoutAlpha")!.alpha(0.5) let myButton = UIButton()  myButton.setBackgroundImage(img, for: .normal)