Text field not moving

import UIKit

class ViewController: UIViewController {

    @IBOutlet var nameTextField: UITextField!
    @IBOutlet var textFieldBottumConstraint: NSLayoutConstraint!

    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardWillShow), name: Notification.Name.UIKeyboardWillHide, object: nil)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "startAdventure" {

            do {
                if let name = nameTextField.text {
                    if name == "" {
                        throw AdventureError.nameNotProvided
                    } else {
                        guard let pageController = segue.destination as? PageController else {
                            return }

                        pageController.page = Adventure.story(withName: name)
                    }
                }
        } catch AdventureError.nameNotProvided {
            let alertController = UIAlertController(title: "Name Not Provided", message: "Provide a name to start the story", preferredStyle: .alert)

            let action = UIAlertAction(title: "OK", style: .default, handler: nil)
            alertController.addAction(action)
            present(alertController, animated: true, completion: nil)
            }catch let error {
                fatalError("\(error.localizedDescription)")
            }
        }
    }

    @objc func keyboardWillShow(_ notification: Notification) {
        if let info = notification.userInfo, let keyboardFrame = info["UIKeyboardFrameEndUserInfoKey"] as? NSValue {
            let frame = keyboardFrame.cgRectValue
            textFieldBottumConstraint.constant = frame.size.height + 10

            UIView.animate(withDuration: 0.8) {
                self.view.layoutIfNeeded()
            }
        }
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }
}