A UINavigationController manages a stack of screens with the familiar back button.
Push a new screen
let detail = DetailVC()
detail.userId = 42 // pass data forward
navigationController?.pushViewController(detail, animated: true)Go back / present modally
navigationController?.popViewController(animated: true)
// modal
present(SettingsVC(), animated: true)Passing data back
Use a closure or a delegate to send results back to the previous screen.
// in DetailVC
var onDone: ((String) -> Void)?
// caller sets detail.onDone = { result in ... }Summary
Navigation controllers manage a screen stack. Pass data forward via properties and back via closures/delegates.