Error to variable transition on other page

Question

I'm creating a greeting app that users can enter their names and the app return "Hello Jack!".

Error Message

Type 'UIViewController' has no member 'textFieldString'

How can I fix it, since I have already setted the variable on ViewController.swift.

        textFieldString = textField.text!

Codes

ViewController.swift

import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var textField: UITextField!
    [![enter image description here][1]][1]
    var textFieldString = ""

    @IBAction func pushButton(_ sender: UIButton){
        textFieldString = textField.text!
        textField.text = ""
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        let resultViewController = segue.destination as! ResultViewController
        resultViewController.result = textFieldString
    }

    @IBAction func unwind(_ segue: UIStoryboardSegue) {

    }



}

ResultViewController.swift

import UIKit

class ResultViewController: UIViewController {
    @IBOutlet weak var label: UILabel!
    var result: String?

    override func viewDidLoad() {
            super.viewDidLoad()

               label.translatesAutoresizingMaskIntoConstraints = false
               label.topAnchor.constraint(equalTo: self.view.topAnchor).isActive = true
               label.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
               label.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true
               label.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true

        label.text = "Hello\(result)! "
           }
}

Screenshots

Answer 1

Reason:

textFieldString is a property of ViewController and not UIViewController.

Solution:

Create a property result in ResultViewController and set it to label in viewDidLoad().

class ResultViewController: UIViewController {
    @IBOutlet weak var label: UILabel!
    var result: String?

    override func viewDidLoad() {
        super.viewDidLoad()
        //rest of the code...
        label.text = "Hello\(result ?? "")" //here...
    }
}

Now in ViewController's prepare(for:sender:) method set result to textFieldString, i.e.

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    let resultViewController = segue.destination as! ResultViewController
    resultViewController.result = textField.text
}