image_color.md

How to change color of image in Swift 4

Let's say we need to change the image of a button when it is clicked, how do we do that?

There is an extension we can make use of and use the function tintImage to specify the color we would like to change the image.

  extension UIImage {

      func tintImage(color: UIColor) -> UIImage {

          UIGraphicsBeginImageContext(self.size)
          guard let context = UIGraphicsGetCurrentContext() else { return self }
          guard let cgImage = cgImage else { return self }

          // flip the image
          context.scaleBy(x: 1.0, y: -1.0)
          context.translateBy(x: 0.0, y: -size.height)

          // multiply blend mode
          context.setBlendMode(.multiply)

          let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
          context.clip(to: rect, mask: cgImage)
          color.setFill()
          context.fill(rect)

          // create uiimage
          guard let newImage = UIGraphicsGetImageFromCurrentImageContext() else { return self }
          UIGraphicsEndImageContext()

          return newImage
      }

  }

And it can be used like this:

  let image = btnClose.imageView?.image?.tintImage(color: UIColor(red: 103/255, green: 58/255, blue: 183/255, alpha: 1))
  btnClose.setImage(image, for: .normal)