Why Doesn't Swift 3 recognize me button tap? - swift

Question

let playButton: UIButton = {
let button = UIButton()
let image = UIImage(named: "VideoIcon.png") as UIImage?
button.backgroundImage(for: .normal)
button.addTarget(self, action: #selector(pressBackButton(button:)), for: .touchUpInside)
button.setImage(image, for: .normal)
return button
}()
func pressBackButton(button: UIButton) {
print("test")
if let playVideoButtonURL = post?.videourl {
let player = AVPlayer(url: playVideoButtonURL as URL)
let playerLayer = AVPlayerLayer(player:player)
playerLayer.frame = CGRect(x: 100, y: 200, width: 100, height: 100)
playerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
self.layer.addSublayer(playerLayer)
player.play()
}
}
even if the video code is wrong it should still print test but it doesn't which is strange. I feel like something may be wrong with the selector but i currently have no idea what could be wrong with it.

Answer 1

access function or property in self outside of initializer.
class TestViewController: UIViewController {
let playButton: UIButton = {
let button = UIButton()
let image = UIImage(named: "VideoIcon.png") as UIImage?
button.backgroundImage(for: .normal)
button.setImage(image, for: .normal)
return button
}()
override func viewDidLoad() {
super.viewDidLoad()
button.addTarget(self, action: #selector(pressBackButton(button:)), for: .touchUpInside)
}
}

Answer 2

Instead of doing:
let playButton: UIButton = {
...
...
return button
}()
which won't work (because you're attempting to create playButton at the wrong time -- which is before the view is loaded or before it's about to appear)
In your viewDidLoad or viewWillAppear, create the button, define the target and simply add it as a subview.
override func viewDidLoad() {
super.viewDidLoad()
let button = UIButton()
if let image = UIImage(named: "VideoIcon.png") as UIImage?
{
button.backgroundImage(for: .normal)
button.addTarget(self, action: #selector(pressBackButton(button:)), for: .touchUpInside)
button.setImage(image, for: .normal)
}
self.addSubview(button)
}
Adding the button as a subview increments the retain count (i.e. it won't go away), but if you want to keep it around as a property simply declare it as:
var playButton : UIButton?
and then set playButton = button at the end of viewDidLoad.