import UIKit

var g_but = MY_UIButton(frame: CGRect(x: 100, y: 100,width: 200,height: 200))
let g_false = false
let opt_zero : Int? = 0
class EMPTY_CLASS {}
let g_empty_arr : [EMPTY_CLASS] = []

class ViewController: UIViewController
{
    override func viewDidAppear(_ animated: Bool)
    {
        super.viewDidAppear(animated)
        g_but.backgroundColor = UIColor.red
        view.addSubview(g_but)
        g_but.addTarget(g_but,action: #selector(MY_UIButton.touchDown(_:)), for:.touchDown)
    }
}
 
class MY_UIButton : UIButton
{
    @objc func touchDown(_: MY_UIButton?)
    {
        if (opt_zero! >= g_empty_arr.count) {}
        let zero_str = (opt_zero == nil) ? "" : "\(opt_zero!)"
        if (g_false) {  print(zero_str) }
        if (opt_zero! >= g_empty_arr.count) {}
    }
}