How to programmatically create the initial view controller, window etc. Swift 3.0

AppDelegate.swift

//
//  AppDelegate.swift
//

import UIKit

@UIApplicationMain

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    let navController = UINavigationController(rootViewController: ViewController()) // ViewController is the initial view controller

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

        // Override point for customization after application launch.

        // Setup the project automatically. 
        // Remember to remove the key-value pair for key "Main storyboard file base name" from Info.plist
        // Delete the storyboard file Main.storyboard

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

        guard let window = window else{

            return false

        }

        navController.isNavigationBarHidden = true // Hide the navigation bar

        window.backgroundColor = UIColor.white

        window.rootViewController = navController

        window.makeKeyAndVisible()

        return true

    }

}