create alert in swift
class ViewController: UIViewController {
    @IBAction func showAlertButtonTapped(_ sender: UIButton) {
        // create the alert
        let alert = UIAlertController(title: "My Title", message: "This is my message.", preferredStyle: .alert)
        // add an action (button)
        alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
        // show the alert
        self.present(alert, animated: true, completion: nil)
    }
}
