Разработка мобильного приложения iOS для новичков

@IBAction func showMessage(sender: UIButton) {
    let alertController = UIAlertController(title: "Welcome to My First App", message: "Hello World", preferredStyle: UIAlertController.Style.alert)
    alertController.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
    present(alertController, animated: true, completion: nil)
}

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    @IBAction func showMessage(sender: UIButton) {
        let alertController = UIAlertController(title: "Welcome to My First App", message: "Hello World", preferredStyle: UIAlertController.Style.alert)
        alertController.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
        present(alertController, animated: true, completion: nil)
    }
}