swift实践笔记

使用代码创建 主视图

funcapplication(_application:UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey:Any]?) ->Bool{

        //创建window

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

        window?.makeKeyAndVisible()

        //设置主视图

        letmainVC =MainViewController()

        letmainNav =UINavigationController(rootViewController:mainVC)

        window?.rootViewController= mainNav

        return true

    }