How to make a controller independent in App Delegate? - swift

Question

So in the AppDelegate.swift file I have a UINavigationController as the root view controller and a mainController as the topViewController for the navigationController. I have all the data instantiated here so it can be independent. Now, I wanted to make MenuController as my topViewController but I'm not sure how to call the mainController from here.
To be more specific, I am creating a crossword game and I've been focusing on the logic and implementation of the grid and such. Now I wanted to make a Menu as my first screen before displaying the crossword game.
MainMenu -> MenuController
CrosswordGame -> MainController
Here is the code I have without the MainMenu implementation in the AppDelegate.swift
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
// Create a ButtonStore
let buttonStore = ButtonStore()
let levelStore = LevelStore()
// Access the MainController and set its buttonStore
let navController = window!.rootViewController as! UINavigationController
let mainController = navController.topViewController as! MainController
mainController.buttonStore = buttonStore
mainController.levelStore = levelStore
return true
}
And here is what I have now
// Create a ButtonStore
let buttonStore = ButtonStore()
let levelStore = LevelStore()
// Access the MainController and set its buttonStore
let navController = window!.rootViewController as! UINavigationController
let menuController = navController.topViewController as! MenuController
// Instantiate MainController and add buttonStore / levelStore to MainController
return true
I just don't want my Crossword Game to lose its data when pressing the back key back to the MainMenu. Another question is, is it viable to put it in the AppDelegate or instantiate the MainController in the MenuController.

Answer 1

//create your view controllers and set any properties
let game = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "mainControllerIdentifier")
let menu = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "menuControllerIdentifier")
//create the navigation controller
let navigationController = UINavigationController()
//set the content controllers on the nav controller
navController.setViewControllers([game, menu], animated: false)
//assign the navigation controller as the root controller of the window
window.rootViewController = navigationController