ViewController.swift

import UIKit

class ViewController: UIViewController {
    
    @IBOutlet weak var loginTextField: UITextField!
    
    @IBOutlet weak var passwordTextField: UITextField!
    
    @IBOutlet weak var resultLabel: UILabel!
    
    @IBAction func loginButton(_ sender: UIButton) {
        performSegue(withIdentifier: "detailSegue", sender: nil)
    }
    
    @IBAction func unWideSegueToMainScreen (segue: UIStoryboardSegue){
        guard segue.identifier == "unwindSegue" else { return }
        guard let svc = segue.source as? SecondViewController else { return }
        if let logOut = svc.login {
            self.resultLabel.text = "Goodbye, \(logOut)"
        }
    }
    
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        guard let dvc = segue.destination as? SecondViewController else { return }
        dvc.login = loginTextField.text
    }
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        self.view.endEditing(true)
    }
    
}