AppDelegate.swift

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    private var myTabBarController: UITabBarController!
    
    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        
        window = UIWindow(frame: UIScreen.mainScreen().bounds)
        
        let myFirstTab: UIViewController = FirstViewController()
        let mySecondTab: UIViewController = SecondViewController()
        
        let myTabs = NSArray(objects: myFirstTab, mySecondTab)
        
        myTabBarController = UITabBarController()
        
        myTabBarController?.setViewControllers(myTabs as?[UIViewController], animated: false)
        
        
        self.window!.rootViewController = myTabBarController
        
        self.window!.makeKeyAndVisible()
        
        return true
    }