1、导航控制器
self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
self.window.backgroundColor = [UIColor blackColor];
[self.window makeKeyAndVisible];
FirstViewController * vc = [[FirstViewController alloc] init];
//视图控制器的管理器
UINavigationController * nav = [[UINavigationController alloc] initWithRootViewController:vc];
self.window.rootViewController = nav;
//进入下一页
[self.navigationController pushViewController:thirdVC animated:YES];
//返回首页
[self.navigationController popToRootViewControllerAnimated:YES];
//返回上一页
[self.navigationController popViewControllerAnimated:YES];