Why doesn’t 'self.navigationController?.pushViewController(mainPage, animated: true)' work?

Question

I am making a basic app that lets users sign up and login and they will be directed to the main page which has horizontal scrolling and paging enabled. The main view has 3 views which you can swipe left or right to go to the other pages. Here is the code where I set the root view controller. NOTE: Only if the user has logged in this view controller will be displayed.

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

        FirebaseApp.configure()

        window = UIWindow(frame: UIScreen.main.bounds)

        let homeScreen = MainScreen()
        let navBar = UINavigationController(rootViewController: homeScreen)
        window?.rootViewController = navBar
        window?.makeKeyAndVisible()


        return true
    }
}

I want to display the main page once the user logs in, but the main page doesn't get displayed. Here is the code when the user taps on the login button, I've only given the necessary code:

// User found and verified, go to main page
let mainPage = MainScreen()
self.navigationController?.pushViewController(mainPage, animated: true)

The pushViewController doesn't work.

Did you try implementing the perfomSegueWithIdentifier method? Once the user is authenticated, try calling this method. — ojassethi, Jun 20 '19 at 07:33
@Abdullah In both the cases you are using the same controller MainScreen(). Make sure you use right screens. — Pavan Kotesh, Jun 20 '19 at 07:35
Do you need a storyboard for this? Cuz I don't use storyboards — Abdullah Ajmal, Jun 20 '19 at 07:37
@PavanKotesh I am using the correct controller, it's just that if the user is already logged in the first controller would be the main screen if not the login screen and once the user logs in the main screen will be displayed — Abdullah Ajmal, Jun 20 '19 at 07:38
This post could be helpful- https://stackoverflow.com/questions/26753925/set-initial-viewcontroller-in-appdelegate-swift — Anupam Mishra, Jun 20 '19 at 07:40
MainScreen() its a function or just an instance from your Viewcontroller ? — A.Munzer, Jun 20 '19 at 08:13
Did you change main interface to nil from project target deployment info? — atalayasa, Jun 20 '19 at 08:44

score 0 · Answer 1 · answered Jun 20 '19 at 08:24

0

Make sure that before you push a viewcontroller your root view controller must be a navigation view controller otherwise it will not work.

answered Jun 20 '19 at 08:24

Nathaniel Gonzales

66
3

score 0 · Answer 2 · answered Jun 20 '19 at 09:21

0

thanks for your answers but I figured it out.

// User found and verified, go to main page
let mainPage = MainScreen()
let navController = UINavigationController(rootViewController: mainPage)
self.present(navController, animated: true, completion: nil)

answered Jun 20 '19 at 09:21

Abdullah Ajmal

431
5
17

the answer is totally different from what you asked in the question. In the question you are pushing a MainScreen view controller on the current navigation controller and the answer suggests presenting it. – kerry Jun 20 '19 at 12:21

Why doesn’t 'self.navigationController?.pushViewController(mainPage, animated: true)' work?

2 Answers2