Adding a target to a button prints out an error - swift

Question

I have the following code:
for i in 0...album.count-1 {
let button: UIButton = {
let bt = UIButton()
bt.translatesAutoresizingMaskIntoConstraints = false
bt.tintColor = UIColor.black
bt.backgroundColor = .clear
bt.addTarget(self, action: #selector(buttonPressed(sender: button, image: imageView)), for: .touchUpInside)
bt.tag = i
buttonPosition += 160
bt.layer.cornerRadius = 5
return bt
}()
//Stuff that you don't need
let imageView: UIImageView = {
let iv = UIImageView()
iv.image = images[i]
iv.contentMode = .scaleAspectFill
iv.clipsToBounds = true
iv.translatesAutoresizingMaskIntoConstraints = false
return iv
}()
}
#objc func buttonPressed(sender: UIButton!, image: UIImageView!) {
let animator = UIViewPropertyAnimator.init(duration: 0.2, curve: .linear) {
image.transform = CGAffineTransform.init(translationX: (image.frame.width + 12) * -1, y: image.frame.origin.y )
}
animator.startAnimation()
}
It prints out this error:
Variable used within its own initial value
What can I do to create a func that uses as parameters that button and that imageView that I created into the cycle?
In the end, how can I create a local func?

Answer 1

You're referring to button from within the very closure that creates it (in the selector clause), which is why you're getting this error. It should work fine if you change #selector(buttonPressed(sender: button, image: imageView)) to #selector(buttonPressed(sender: bt, image: imageView)). However, a cleaner way to do this would be to create a factory function, e.g.:
func makeButton(at position: CGFloat, taggedWith tag: Int) -> UIButton {
let bt = UIButton()
bt.translatesAutoresizingMaskIntoConstraints = false
bt.tintColor = UIColor.black
bt.backgroundColor = .clear
bt.addTarget(self, action: #selector(buttonPressed(sender: button, image: imageView)), for: .touchUpInside)
bt.tag = tag
/// buttonPosition += 160 /// not sure what this is supposed to do but you'd use the position param here.
bt.layer.cornerRadius = 5
return bt
}
You would then call this function to make buttons in your loop. Note that buttonPosition appears to be unused. Also note that your buttons weren't added to a collection or a view so you may want to examine where the buttons are supposed to live and place them accordingly.