3.UITabBarController实现并列画面跳转
//将5个ViewController实例放入TabBar的viewControllers属性中
self.tabBarController.viewControllers = @[navFirst, navSecond, navThird, navFourth, navFifth];
self.window.rootViewController = self.tabBarController;
//将根控制器的视图加到应用程序的主窗口
[self.window addSubview: self.tabBarController.view];
4.UINavigationController实现多层画面跳转,在导航控制器中,载入有层级关系的界面
[self.navigationController pushViewController: ... animated: ... ];
//弹出后返回到原视图
[self.navigationController popViewController: ... animated: ... ];