Ask user for a number in Swift (iOS)

UIViewController+askNumber.swift

import UIKit

extension UIViewController {
    func ask(title: String?, question: String?, placeholder: String?, keyboardType: UIKeyboardType = .default, delegate: @escaping (_ answer: String?) -> Void) {
        let alert = UIAlertController(title: title, message: question, preferredStyle: .alert)
        alert.addTextField { (textField) in
            textField.placeholder = placeholder
            textField.keyboardType = keyboardType
        }
        alert.addAction(UIAlertAction(title: "OK", style: .default) { (_) in
            let answer = alert.textFields?.first?.text
            delegate(answer)
        })
        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel) { (_) in
            delegate(nil)
        })
        present(alert, animated: true, completion: nil)
    }
    
    func askNumber(title: String?, question: String?, placeholder: String?, delegate: @escaping (_ answer: Int?) -> Void) {
        ask(title: title, question: question, placeholder: placeholder, keyboardType: .numberPad) { (result) in
            if let result = result,
               let iResult = Int(result) {
                delegate(iResult)
            } else {
                delegate(nil)
            }
        }
    }
}