button function

ViewController.swift

@IBAction func showMessage(sender: UIButton) {
        let alertController = UIAlertController(title: "Alert", message: enabled ? "Hello World!" : "Nothing to see here...", preferredStyle: UIAlertController.Style.alert)
    
        var enabled = false
  
        if enabled {
            alertController.addAction(UIAlertAction(title: "Hello!", style: UIAlertAction.Style.default, handler: nil))
        } else {
            alertController.addAction(UIAlertAction(title: "Ok", style: UIAlertAction.Style.default, handler: nil))
        }
        
        present(alertController, animated: true, completion: nil)
    }