How to make a button flash or blink?

Question

I am trying to change a button\'s color (just a flash/blink) to green when a scan is correct and red when there\'s a problem. I am able to do this with a view like so

Answer 1

This should work in Swift 4

extension UIView{
     func blink() {
         self.alpha = 0.2
         UIView.animate(withDuration: 1, delay: 0.0, options: [.curveLinear, .repeat, .autoreverse], animations: {self.alpha = 1.0}, completion: nil)
     }
}