新建工程后删除viewController.h和viewController.m main.storyboard
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
//创建窗口
self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];//初始化Window
UITabBarController * tabBarVc = [[UITabBarController alloc]init];
self.window.rootViewController = tabBarVc;//设置根视图控制器
//显示窗口
[self.window makeKeyAndVisible];
return YES;
}