UIViewController+UIAlertController.swift

extension UIViewController {
   func showAlert(withTitle title: String, message: String, actionTitle: String) {
      let alertController = UIAlertController(title: title, message: message, preferredStyle: .alert)
      let action = UIAlertAction(title: actionTitle, style: .default, handler: nil)
      alertController.addAction(action)
      present(alertController, animated: true, completion: nil)
   }
}