let storyboard = UIStoryboard(name: "Main", bundle: nil)
let mainViewController = storyboard.instantiateInitialViewController() as! MainViewController
self.navigationController.pushViewController(mainViewController, animated: true)

import UIKit

// MARK: - Coordinator
protocol Coordinator: class {
  var finishDelegate: CoordinatorFinishDelegate? { get set }
  // Each coordinator has one navigation controller assigned to it.
  var navigationController: UINavigationController { get set }
  /// Array to keep tracking of all child coordinators. Most of the time this array will contain only one child coordinator
  var childCoordinators: [Coordinator] { get set }
  /// Defined flow type.
  var type: CoordinatorType { get }
  /// A place to put logic to start the flow.
  func start()
  /// A place to put logic to finish the flow, to clean all children coordinators, and to notify the parent that this coordinator is ready to be deallocated
  func finish()
  
  init(_ navigationController: UINavigationController)
}

extension Coordinator {
  func finish() {
    childCoordinators.removeAll()
    finishDelegate?.coordinatorDidFinish(childCoordinator: self)
  }
}

// MARK: - CoordinatorOutput
/// Delegate protocol helping parent Coordinator know when its child is ready to be finished.
protocol CoordinatorFinishDelegate: class {
  func coordinatorDidFinish(childCoordinator: Coordinator)
}

// MARK: - CoordinatorType
/// Using this structure we can define what type of flow we can use in-app.
enum CoordinatorType {
  case app, login, tab
}

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
            
    window = UIWindow.init(frame: UIScreen.main.bounds)
    
    let navigationController: UINavigationController = .init()

    window?.rootViewController = navigationController
    window?.makeKeyAndVisible()
    
    appCoordinator = AppCoordinator.init(navigationController)
    appCoordinator?.start()
            
    return true
}

let homeStoryboard = UIStoryboard(name: "Home", bundle: nil)
let homeVC = homeStoryboard.instantiateViewController(withIdentifier: "HomeVC") as! HomeViewController
self.homeViewController = homeVC

self.homeVC = HomeViewController()