删除StoryBorad

1.删除Main.storyboard和LaunchScreen

2.设置Main Interface和Launch Screen File为空

3.AppDelegate 的didFinishLaunchingWithOptions中设置          

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

    window?.backgroundColor=UIColor.white

    window?.rootViewController =  自定义需要展示的视图控制器

    window?.makeKeyAndVisible()

    return true