UINavigationController相关

//跳转到自己想要的控制器

- (NSArray *)popToViewController:(UIViewController *)viewController animated:(BOOL)animated;
//就是导航栈stack的栈顶
topViewController

//如果有模态视图就是模态视图，否则就是topViewController

visibleViewController是当前展示的viewController

//隐藏导航栏

- (void)setNavigationBarHidden:(BOOL)hidden
animated:(BOOL)animated;

//隐藏工具栏

- (void)setToolbarHidden:(BOOL)hidden
animated:(BOOL)animated

//弹出键盘时候隐藏导航栏（>=iOS8）

hidesBarsWhenKeyboardAppears

//滚动时候隐藏导航栏(>=iOS8)

hidesBarsOnSwipe

//拉到底部时候隐藏导航栏(>=iOS8)

hidesBarsWhenVerticallyCompact

//push的控制器没有底部Tabbar

hidesBottomBarWhenPushed

//设置底部tabbar的item

setToolbarItems

//UINavigationControllerDelegate

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated;
- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated;