Swift - "navigationController?.pushViewController" doesn't work - swift

Question

I have 3 ViewControllers like below.
A: HomeController,
B: NavController1,
C: NavController2
I set a custom navigation bar in B and C and I use "navigationController?.pushViewController" for the segues From A to B to C.
These are the codes.
Custom navigation bar:
class CustomNavBar: UINavigationBar {
let navBarView: UIView = {
let view = UIView()
view.backgroundColor = .black
// Logo
let logo = UIImageView(image: <image-file>)
view.addSubview(logo)
logo.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
logo.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
return view
}()
public func setupNavBar() {
if let window = UIApplication.shared.keyWindow {
window.addSubview(navBarView)
navBarView.topAnchor.constraint(equalTo: window.topAnchor, constant: 0).isActive = true
navBarView.leftAnchor.constraint(equalTo: window.leftAnchor, constant: 0).isActive = true
navBarView.rightAnchor.constraint(equalTo: window.rightAnchor, constant: 0).isActive = true
}
}
}
And in the ViewControllers B and C I put these codes.
class NavController1: UIViewController {
let navBar = CustomNavBar()
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
navBar.setupNavBar()
}
override func viewWillDisappear(_ animated: Bool) {
loginHeader.headerBg.isHidden = true
loginHeader.backButton.isHidden = true
}
}
And for the segues, I used the code below with a UIButton action.
self.navigationController?.pushViewController(NavController1, animated: true)
It works with the segue from A to B but it doesn't work with B to C.
Can someone point out what the problem is? Thank you!

Answer 1

UINavigationController is derived from UIViewController, which means it has a navigationController property. Thing is, this will be nil on the actual UINavigationController because it doesn't have a navigation controller, it is the navigation controller. Because you are using optional chaining, the message is never getting sent because navigationController is nil. Try sending the message to self instead (given that self is of type UINavigationController, and the current one).
I.E. self.pushViewController(NavController1, animated: true)