UIButton transition - swift

Question

I have a group of six buttons - when one is pressed (programmatically) I would like it to light up and then fade out. So I created a function called lightUp(button: UIButton). I also have two images for each button - lit and unlit. I can go from the default unlit to lit, but so far, trying to light the button first, before fading it back to unlit has been a problem. In the code below, the buttons don't light up at all.
func lightUp(button: UIButton){
button.setImage(UIImage(named: padArrayOn[button.tag]), for: .normal)
UIView.transition(with: button, duration: 0.4, options: .transitionCrossDissolve, animations: {
button.setImage(UIImage(named: self.padArrayOff[button.tag]), for: .normal)
}) { (bool) in
self.playSequence()
}
}

Answer 1

Set two transitions, the second in the completion handler of the first perhaps?
func lightUp(button: UIButton){
UIView.transition(with: button, duration: 0.2, options: .transitionCrossDissolve, animations: {
button.setImage(UIImage(named: padArrayOn[button.tag]), for: .normal)
}, completion: {_ in
UIView.transition(with: button, duration: 0.2, options: .transitionCrossDissolve, animations: {
button.setImage(UIImage(named: self.padArrayOff[button.tag]), for: .normal)
}, completion: { _ in
self.playSequence()
}
)})
}

Answer 2

if I understood you correctly you want to light up the button (maybe change the background) and then it should fade out.
You can try something like this:
func lightUpAndFadeOut(button: UIButton){
UIView.animate(withDuration: 2) {
button.backgroundColor = UIColor.red
}
UIView.animate(withDuration: 5) {
button.alpha = 0
}
}
Every button calls this function and it should look like this:
lightUpAndFadeOut(button: sender as! UIButton)
Correct?