import UIKit class AViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() self.view.backgroundColor = .red // Do any additional setup after loading the view. } }

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) { // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`. // If using a storyboard, the `window` property will automatically be initialized and attached to the scene. // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead). guard let scene = (scene as? UIWindowScene) else { return } let a = UINavigationController(rootViewController: AViewController()) let b = UINavigationController(rootViewController: BViewController()) let c = UINavigationController(rootViewController: CiewController()) a.tabBarItem = UITabBarItem(title: "AAA", image: nil, selectedImage: nil) b.tabBarItem = UITabBarItem(title: "BBB", image: nil, selectedImage: nil) c.tabBarItem = UITabBarItem(title: "CCC", image: nil, selectedImage: nil) let tabbarVc = UITabBarController() tabbarVc.viewControllers = [a,b,c] window?.backgroundColor = .clear window?.rootViewController = tabbarVc window?.makeKeyAndVisible() }