How to navigate from one View Controller to the other? - swift

Question

I want to navigate from one View Controller to another.
let vc = SecondViewController()
I have tried until now :
vc.modalPresentationController = .fullScreen
self.present(vc, animated: true) //self refers to the main view controller
Im trying to open a new ViewController when the users manages to register or to log in.I am new to software developing, and I want to ask, is this the best method to navigate from one ViewController to another, im asking because as I can see the mainViewController is not deinit(). I have found other similar questions and tried the answers, the problem is with the:
self.navigationController?.pushViewController
it doesn't work because I don't have any storyboard.
The question is it is right to navigate as explained above?
Thanks,

Answer 1

Typically when you are doing login you would use neither push or present. There are multiple ways of handling this, but the easiest is to embed in some parent (root) VC. Here is an example:
class ViewController: UIViewController {
private var embeddedViewController: UIViewController! {
didSet {
// https://developer.apple.com/documentation/uikit/view_controllers/creating_a_custom_container_view_controller
// Add the view controller to the container.
addChild(embeddedViewController)
view.addSubview(embeddedViewController.view)
// Create and activate the constraints for the child’s view.
embeddedViewController.view.translatesAutoresizingMaskIntoConstraints = false
embeddedViewController.view.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
embeddedViewController.view.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
embeddedViewController.view.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
embeddedViewController.view.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
// Notify the child view controller that the move is complete.
embeddedViewController.didMove(toParent: self)
}
}
override func viewDidLoad() {
super.viewDidLoad()
let loginVC = LoginViewController()
loginVC.delegate = self
embeddedViewController = loginVC
}
}
extension ViewController: LoginDelegate {
func didLogin() {
embeddedViewController = MainViewController()
}
}
protocol LoginDelegate: AnyObject {
func didLogin()
}
class LoginViewController: UIViewController {
private lazy var loginButton: UIButton = {
let button = UIButton()
button.setTitle("Login", for: .normal)
button.addTarget(self, action: #selector(didTapLoginButton), for: .touchUpInside)
return button
}()
weak var delegate: LoginDelegate?
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(loginButton)
view.backgroundColor = .red
loginButton.translatesAutoresizingMaskIntoConstraints = false
loginButton.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
loginButton.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
}
#objc private func didTapLoginButton() {
delegate?.didLogin()
}
}
class MainViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .blue
}
}