How to use AppFlowController in iOS

import UIKit
import GoogleMaps
import Stripe

final class AppFlowController: UIViewController {
    private lazy var window = UIWindow(frame: UIScreen.main.bounds)

    func configure() {
        GMSServices.provideAPIKey(Constant.googleMapsApiKey)
        STPPaymentConfiguration.shared().publishableKey = Constant.stripeKey
    }

    func start() {
        if Deps.onboardingHandler.hasOnboarded {
            startMain()
        } else {
            startOnboarding()
        }

        window.makeKeyAndVisible()
    }

    func startOnboarding() {
        let controller = OnboardingController()
        controller.delegate = self
        window.rootViewController = controller
    }

    func startMain() {
        let controller = MainFlowController()
        window.rootViewController = controller
        controller.start()
    }
}

extension AppFlowController: OnboardingControllerDelegate {
    func onboardingControllerDidFinish(_ controller: OnboardingController) {
        Deps.onboardingHandler.hasOnboarded = true
        startMain()
    }
}

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    private let appFlowController = AppFlowController()

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

        appFlowController.configure()
        appFlowController.start()

        UIApplication.shared.registerForRemoteNotifications()
		FirebaseApp.configure()
        return true
    }
}