Can not set the value in the label using delegate protocol - ios

Question

enter image description herei am making a program with delegate protocol in which we add value in text field in second controller and click save and this value is set to the label in the previous viewController
all the this are done but the value can not set to the label
Can someone please explain me what is triggering the messageData() method in the main ViewController?
import UIKit
protocol SenderViewControllerDelegate {
func messageData(data: String)
}
class NewViewController: UIViewController {
//MARK:- Properties
#IBOutlet weak var firstTextField: UITextField!
var delegate: SenderViewControllerDelegate?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func SaveFirstValue(_ sender: Any) {
if delegate != nil{
if firstTextField.text != nil{
let data = firstTextField.text
delegate?.messageData(data: data!)
dismiss(animated: true, completion: nil)
}
}
}
}
import UIKit
class ViewController: UIViewController,SenderViewControllerDelegate {
//MARK:- Properties
#IBOutlet var firstLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//MARK:- Actions
func messageData(data: String) {
firstLabel.text = data
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showSendingVc" {
let viewController : ViewController = segue.destination as! NewViewController
ViewController.delegate = self
}
}
}

Answer 1

Change this line
let viewController = segue.destination as! NewViewController
viewController.delegate = self

Answer 2

`ViewController.delegate = self` should be `viewController.delegate = self`
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showSendingVc" {
let viewController : NewViewController = segue.destination as! NewViewController //destination is type NewViewController not ViewController
// ViewController.delegate = self //Wrong
viewController.delegate = self
}
}

Answer 3

You made mistake in the line ViewController.delegate = self it should be
viewController.delegate = self
means small "v" (object of ViewController)
UPDATED:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showSendingVc" {
let objectOfVC = segue.destination as! NewViewController
objectOfVC.delegate = self
}
}

Answer 4

In ViewController Class set the delegate inside ViewDidLoad method like this:
newViewControllerObj. delegate = self
Without calling viewController Class, the delegate will not set So you have to call ViewController class inside NewViewController or other class which will call first like that:
let ViewControllerObj = ViewController()