typedef NS_ENUM(NSInteger, UINavigationControllerOperation) {
    UINavigationControllerOperationNone,
    UINavigationControllerOperationPush,
    UINavigationControllerOperationPop,
};

UIKIT_EXTERN const CGFloat UINavigationControllerHideShowBarDuration;

@class UIView, UINavigationBar, UINavigationItem, UIToolbar, UILayoutContainerView;
@protocol UINavigationControllerDelegate;

#pragma - mark - --
NS_CLASS_AVAILABLE_IOS(2_0) @interface UINavigationController : UIViewController

// 可以添加 navigationBarClass 或其子类，toolbarClass 也是一样的。
- (instancetype)initWithNavigationBarClass:(Class)navigationBarClass toolbarClass:(Class)toolbarClass NS_AVAILABLE_IOS(5_0);
// 初始化根控制器
- (id)initWithRootViewController:(UIViewController *)rootViewController;

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated; // 推到下一个界面

- (UIViewController *)popViewControllerAnimated:(BOOL)animated; // 返回上一个界面

- (NSArray *)popToViewController:(UIViewController *)viewController animated:(BOOL)animated; // 返回到上几个界面，返回被推出的控制器的数组

- (NSArray *)popToRootViewControllerAnimated:(BOOL)animated; // 返回到根界面

// 栈顶控制器
@property(nonatomic,readonly,retain) UIViewController *topViewController;
// 当前可见视图所属的控制器
@property(nonatomic,readonly,retain) UIViewController *visibleViewController;
// 所有的栈里地控制器
@property(nonatomic,copy) NSArray *viewControllers;
- (void)setViewControllers:(NSArray *)viewControllers animated:(BOOL)animated NS_AVAILABLE_IOS(3_0);

// 隐藏导航条
@property(nonatomic,getter=isNavigationBarHidden) BOOL navigationBarHidden;
- (void)setNavigationBarHidden:(BOOL)hidden animated:(BOOL)animated;
@property(nonatomic,readonly) UINavigationBar *navigationBar;

// 工具条
@property(nonatomic,getter=isToolbarHidden) BOOL toolbarHidden NS_AVAILABLE_IOS(3_0);
- (void)setToolbarHidden:(BOOL)hidden animated:(BOOL)animated NS_AVAILABLE_IOS(3_0);
@property(nonatomic,readonly) UIToolbar *toolbar NS_AVAILABLE_IOS(3_0);

@property(nonatomic, assign) id<UINavigationControllerDelegate> delegate;
@property(nonatomic, readonly) UIGestureRecognizer *interactivePopGestureRecognizer NS_AVAILABLE_IOS(7_0);
@end

@protocol UIViewControllerInteractiveTransitioning;
@protocol UIViewControllerAnimatedTransitioning;

@protocol UINavigationControllerDelegate <NSObject>

@optional
// 将要显示某一个控制器
- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated;
// 已经显示某一个控制器
- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated;
// 支持的旋转方向
- (NSUInteger)navigationControllerSupportedInterfaceOrientations:(UINavigationController *)navigationController NS_AVAILABLE_IOS(7_0);

- (UIInterfaceOrientation)navigationControllerPreferredInterfaceOrientationForPresentation:(UINavigationController *)navigationController NS_AVAILABLE_IOS(7_0);

- (id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
                          interactionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);

- (id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                   animationControllerForOperation:(UINavigationControllerOperation)operation
                                                fromViewController:(UIViewController *)fromVC
                                                  toViewController:(UIViewController *)toVC  NS_AVAILABLE_IOS(7_0);

@end

@interface UIViewController (UINavigationControllerItem)
// 导航条组件
@property(nonatomic,readonly,retain) UINavigationItem *navigationItem;
@property(nonatomic) BOOL hidesBottomBarWhenPushed;
@property(nonatomic,readonly,retain) UINavigationController *navigationController;

@end

@interface UIViewController (UINavigationControllerContextualToolbarItems)

@property (nonatomic, retain) NSArray *toolbarItems NS_AVAILABLE_IOS(3_0);
- (void)setToolbarItems:(NSArray *)toolbarItems animated:(BOOL)animated NS_AVAILABLE_IOS(3_0);

@end