This is a custom UINavigationController to manage navigation between each ViewController, it will be used only to navigate with UIKit and work with .xib and not with .storyboard. To know how to use it you can go to see how I use it in the InfoSpace project, which is in my github account. If you have any questions about how to use it, ask away!

CustomNavigationController.swift

//
//  CustomNavigationController.swift
//
//  Created by GonzaloMR
//

import UIKit
import SafariServices

final class CustomNavigationController: UINavigationController {

    // Here we have to create and instantiate the rootViewController
    static let instance = CustomNavigationController(rootViewController: SplashScreenViewController.initAndLoad())

    private override init(rootViewController: UIViewController) {
        super.init(rootViewController: rootViewController)

        // Configure Navigation Controller appearance
        self.view.translatesAutoresizingMaskIntoConstraints = false
        self.setNavigationBarHidden(true, animated: false)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func configureWindow() -> UIWindow {
        // Create a window that is the same size as the screen
        let window = UIWindow(frame: UIScreen.main.bounds)

        window.rootViewController = self
        // Show the window
        window.makeKeyAndVisible()
        
        return window
    }
    
    func navigate(to destination: UIViewController, animated: Bool, closePreviousVC: Bool = false) {
        if let topViewController = UIApplication.topViewController(controller: self), let nav = topViewController.navigationController {
            nav.pushViewController(destination, animated: animated)
            if closePreviousVC {
                if let index = nav.viewControllers.firstIndex(of: destination), index > 0 {
                    nav.viewControllers.removeSubrange(0..<index)
                }
            }
            
        } else {
            self.pushViewController(destination, animated: animated)
            if closePreviousVC {
                if let index = self.viewControllers.firstIndex(of: destination), index > 0 {
                    self.viewControllers.removeSubrange(0..<index)
                }
            }
        }
    }
    
    func present(to destination: UIViewController, animated: Bool, presentationStyle: UIModalPresentationStyle = .overCurrentContext, completion: (() -> Void)? = nil) {
        if let topViewController = UIApplication.topViewController(controller: self) {
            destination.modalPresentationStyle = presentationStyle
            topViewController.present(destination, animated: animated, completion: completion)
        } else {
            destination.modalPresentationStyle = presentationStyle
            self.present(destination, animated: animated, completion: completion)
        }
    }
    
    func dismissVC(animated: Bool, completion: (() -> Void)? = nil) {
        if let topViewController = UIApplication.topViewController(controller: self) {
            if topViewController.isModal() {
                topViewController.dismiss(animated: animated, completion: completion)
            } else {
                topViewController.navigationController?.popViewController(animated: animated)
                completion?()
            }
        } else {
            self.popViewController(animated: animated)
            completion?()
        }
    }
    
    func presentDefaultAlert(title: String, message: String, actionTitle: String = "Okey", completion: ((UIAlertAction) -> Void)? = nil) {
        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: actionTitle, style: .default, handler: completion))
        self.present(alert, animated: true, completion: nil)
    }
    
    func presentAcceptOrCancelAlert(title: String, message: String, acceptActionTitle: String = "Accept", cancelActionTitle: String = "Cancel", acceptCompletion: ((UIAlertAction) -> Void)? = nil, cancelCompletion: ((UIAlertAction) -> Void)? = nil) {
        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
        
        let acceptAction = UIAlertAction(title: acceptActionTitle, style: .default, handler: acceptCompletion)
        let cancelAction = UIAlertAction(title: cancelActionTitle, style: .default, handler: cancelCompletion)
        
        alert.addAction(acceptAction)
        alert.addAction(cancelAction)
        
        self.present(alert, animated: true, completion: nil)
    }
    
    func popToViewController(classVC: AnyClass, animated: Bool) {
        if let viewController = self.getViewControllerInStack(classVC: classVC) {
            self.popToViewController(viewController, animated: animated)
        }
    }
    
    func getViewControllerInStack(classVC: AnyClass) -> UIViewController? {
        return self.viewControllers.first(where: { type(of:$0) == classVC })
    }
    
    func openUrl(_ url: URL) {
        let safariController = SFSafariViewController(url: url)
        
        safariController.modalPresentationStyle = .overFullScreen
        
        self.present(safariController, animated: true, completion: nil)
    }
}