以编程方式将初始视图控制器设置为tab控制器swift 2

import UIKit

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        
        // 创建Tab控制器
        let tabBarController = UITabBarController()
        
        // 创建视图控制器
        let viewController1 = UIViewController()
        viewController1.view.backgroundColor = UIColor.redColor()
        viewController1.tabBarItem = UITabBarItem(title: "Tab 1", image: nil, tag: 0)
        
        let viewController2 = UIViewController()
        viewController2.view.backgroundColor = UIColor.greenColor()
        viewController2.tabBarItem = UITabBarItem(title: "Tab 2", image: nil, tag: 1)
        
        // 将视图控制器添加到Tab控制器
        tabBarController.viewControllers = [viewController1, viewController2]
        
        // 设置初始视图控制器为Tab控制器
        self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
        self.window?.rootViewController = tabBarController
        self.window?.makeKeyAndVisible()
        
        return true
    }
}