Swift transit from vc to another vc - swift

Question

ViewController has a label and a button for go to secondVC. And secondVC has a text field , label , button to write user-entered text in the text field on the label. When user press the back button of navigation bar, I want transit secondVC's label's text to ViewController's label's text. How can I do this ?
ViewController's code:
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var nameLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func goVC2(_ sender: Any) {
performSegue(withIdentifier: "toVC2", sender: nil)
}
}
secondVC's code:
import UIKit
class secondVC: UIViewController {
#IBOutlet weak var nameField: UITextField!
#IBOutlet weak var resultLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func saveClicked(_ sender: Any) {
resultLabel.text = nameField.text
}
}
I tried prepare for segue in ViewController and but it was error. And I searched on google for this but I couldn't find solution.

Answer 1

Use protocol for pass data from second VC to first VC. you need to create your own delegate method and call on dismiss with pass data, check below code :----
ViewController's code:
import UIKit
class ViewController: UIViewController, Delegate {
#IBOutlet weak var nameLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
func save(str : String) {
self.nameLabel.text = str
}
#IBAction func goVC2(_ sender: Any) {
if let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "secondVC") as? secondVC {
vc.delegate = self
self.present(vc, animated: true, completion: nil)
}
}
}
secondVC's code:
import UIKit
protocol Delegate : AnyObject {
func save(str : String)
}
class secondVC: UIViewController {
#IBOutlet weak var nameField: UITextField!
#IBOutlet weak var resultLabel: UILabel!
weak var delegate : Delegate?
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func saveClicked(_ sender: Any) {
if let del = self.delegate {
let txt = nameField.text
del.save(str: txt)
self.dismiss(animated: true, completion: nil)
}
}
}