你真的了解UINavigationController吗？

一：首先查看一下关于UINavigationController的定义

NS_CLASS_AVAILABLE_IOS(2_0) @interface UINavigationController : UIViewController

//UINavigationController初始化,自定义NavigationBar,自定义toolbar
- (instancetype)initWithNavigationBarClass:(nullable Class)navigationBarClass toolbarClass:(nullable Class)toolbarClass NS_AVAILABLE_IOS(5_0);

//UINavigationController初始化,导航控制器的根控制器
- (instancetype)initWithRootViewController:(UIViewController *)rootViewController;

//压栈：将目标控制器压入栈中
- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated; 

//弹栈：将栈顶控制器从栈中弹出
- (nullable UIViewController *)popViewControllerAnimated:(BOOL)animated;

//弹栈：弹到指定的目标控制器
- (nullable NSArray<__kindof UIViewController *> *)popToViewController:(UIViewController *)viewController animated:(BOOL)animated; 

//弹栈：弹到根控制器
- (nullable NSArray<__kindof UIViewController *> *)popToRootViewControllerAnimated:(BOOL)animated;
//导航栈的栈顶视图 只读 就是某个导航栈的栈顶视图，和导航息息相关
@property(nullable, nonatomic,readonly,strong) UIViewController *topViewController; 
//当前显示的控制器 只读 visibleViewController和哪个导航栈没有关系，只是当前显示的控制器，也就是说任意一个导航的visibleViewController所返回的值应该是一样的
@property(nullable, nonatomic,readonly,strong) UIViewController *visibleViewController;

//栈里的视图控制器数组
@property(nonatomic,copy) NSArray<__kindof UIViewController *> *viewControllers;

//替换栈中的视图控制器数组
- (void)setViewControllers:(NSArray<UIViewController *> *)viewControllers animated:(BOOL)animated NS_AVAILABLE_IOS(3_0); 

//是否隐藏导航栏
@property(nonatomic,getter=isNavigationBarHidden) BOOL navigationBarHidden;

//设置导航栏隐藏 是否有动画
- (void)setNavigationBarHidden:(BOOL)hidden animated:(BOOL)animated; 

//导航栏
@property(nonatomic,readonly) UINavigationBar *navigationBar; 

//toolbar是否隐藏
@property(nonatomic,getter=isToolbarHidden) BOOL toolbarHidden NS_AVAILABLE_IOS(3_0);

//toolbar是否隐藏 是否有动画
- (void)setToolbarHidden:(BOOL)hidden animated:(BOOL)animated NS_AVAILABLE_IOS(3_0); 

//toolbar对象
@property(null_resettable,nonatomic,readonly) UIToolbar *toolbar NS_AVAILABLE_IOS(3_0); 

//委托
@property(nullable, nonatomic, weak) id<UINavigationControllerDelegate> delegate;

//边缘侧滑返回手势
@property(nullable, nonatomic, readonly) UIGestureRecognizer *interactivePopGestureRecognizer NS_AVAILABLE_IOS(7_0);

//展示视图控制器
- (void)showViewController:(UIViewController *)vc sender:(nullable id)sender NS_AVAILABLE_IOS(8_0); // Interpreted as pushViewController:animated:

//输入键盘出现时将导航栏隐藏 IOS8特性
@property (nonatomic, readwrite, assign) BOOL hidesBarsWhenKeyboardAppears NS_AVAILABLE_IOS(8_0);

//滚动页面时隐藏Bar  IOS8特性
@property (nonatomic, readwrite, assign) BOOL hidesBarsOnSwipe NS_AVAILABLE_IOS(8_0);

//获取能够隐藏navigationBar的滑动手势 只读
@property (nonatomic, readonly, strong) UIPanGestureRecognizer *barHideOnSwipeGestureRecognizer NS_AVAILABLE_IOS(8_0);

//当设置为true时，横向方向时隐藏NavigationBar
@property (nonatomic, readwrite, assign) BOOL hidesBarsWhenVerticallyCompact NS_AVAILABLE_IOS(8_0);

//当设置为true时，如果有没处理的点击手势就会隐藏和现实navigationBar 
@property (nonatomic, readwrite, assign) BOOL hidesBarsOnTap NS_AVAILABLE_IOS(8_0);

//获取能够隐藏navigationBar的点击手势 只读
@property (nonatomic, readonly, assign) UITapGestureRecognizer *barHideOnTapGestureRecognizer NS_AVAILABLE_IOS(8_0);

@end

知识点1：UINavigationController  UINavigationBar  UINavigationItem三者的关系

通俗地说就是，UINavigationController是个容器，里面可以装很多UIViewController。装这么多UIViewController让用户怎么控制它们呢，总得有个工具吧。这个工具就是UINavigationBar。一个容器就这么一个bar，相当于控制台吧。但是，管理那么多UIViewController，控制台上得按钮啊、标题啊，都千篇一律是不是看起来太无聊了。为了解决这个问题，UINavigationController为每个UIViewController生成一个UINavigationItem，通过这个UINavigationItem可以改变控制台“上面”得按钮和标题。如果你不自定义UINavigationItem，UINavigationController会使用默认的;

UINavigationController是UIViewController的子类，UINavigationBar是UIView的子类。

UINavigationBar是UINavigationController的一个组成部分，就是上面的那个导航栏。

UINavigationBar又有UINavigationItem组成。

UINavigationItem则有title，按钮，提示文本等组成，就是我们看到的title文字，右上角的按钮。 

navigation item在navigation Bar代表一个viewController，具体一点儿来说就是每一个加到navigationController的viewController都会有一个对应的navigationItem一个导航控制器控制多个视图，NavigationBar上的leftItem,rightItem,title是由当前的视图控制器控制的

二：UINavigationControllerDelegate的定义内容

/**
 *  将要显示目标控制器
 *
 *  @param navigationController 当前导航控制器
 *  @param viewController       目标视图控制器
 *  @param animated             动画
 */
- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated;
/**
 *  目标控制器最终显示
 *
 *  @param navigationController 当前导航控制器
 *  @param viewController       目标视图控制器
 *  @param animated             动画
 */
- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated;
/**
 *  横竖屏切换
 *
 *  @param navigationController 当前导航控制器
 *
 *  @return 横竖屏方向
 */
- (UIInterfaceOrientationMask)navigationControllerSupportedInterfaceOrientations:(UINavigationController *)navigationController NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
/**
 *  横竖屏切换
 *
 *  @param navigationController 当前导航控制器
 *
 *  @return 横竖屏方向
 */
- (UIInterfaceOrientation)navigationControllerPreferredInterfaceOrientationForPresentation:(UINavigationController *)navigationController NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
/**
 *  转场动画
 *
 *  @param navigationController 当前导航控制器
 *  @param animationController  动画控制器
 *
 *  @return 转场动画
 */
- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
                                   interactionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);
/**
 *  转场动画
 *
 *  @param navigationController 当前导航控制器
 *  @param operation            动画类型枚举
 *  @param fromVC               起始视图控制器
 *  @param toVC                 目标视图控制器
 *
 *  @return 转场动画
 */
- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                            animationControllerForOperation:(UINavigationControllerOperation)operation
                                                         fromViewController:(UIViewController *)fromVC
                                                           toViewController:(UIViewController *)toVC  NS_AVAILABLE_IOS(7_0);

UINavigationController的delegate方法我平时的开发工作中很少用到

三：UIViewController (UINavigationControllerItem)分类

@interface UIViewController (UINavigationControllerItem)
//导航栏上面用户自定义视图
@property(nonatomic,readonly,strong) UINavigationItem *navigationItem; 
//推送时隐藏bottom
@property(nonatomic) BOOL hidesBottomBarWhenPushed;
//下级视图的导航控制器
@property(nullable, nonatomic,readonly,strong) UINavigationController *navigationController; 

@end

知识点1：UINavigationControllerItem因为扩展在UIViewController上，所以可以直接在UIViewController中使用下面的代码进行调用跟设置；

self.navigationItem.title = @"UINavigationBar使用总结";

四：UIViewController (UINavigationControllerContextualToolbarItems)分类 拓展toolbarItems属性

@interface UIViewController (UINavigationControllerContextualToolbarItems)
//属性设置工具条中包含的按钮
@property (nullable, nonatomic, strong) NSArray<__kindof UIBarButtonItem *> *toolbarItems NS_AVAILABLE_IOS(3_0);
- (void)setToolbarItems:(nullable NSArray<UIBarButtonItem *> *)toolbarItems animated:(BOOL)animated NS_AVAILABLE_IOS(3_0);

@end

五：关于UINavigationBar定义内容

NS_CLASS_AVAILABLE_IOS(2_0) @interface UINavigationBar : UIView <NSCoding, UIBarPositioning> 

@property(nonatomic,assign) UIBarStyle barStyle;

@property(nullable,nonatomic,weak) id<UINavigationBarDelegate> delegate;

//Translucent设置成透明度,设置成YES会有一种模糊效果
@property(nonatomic,assign,getter=isTranslucent) BOOL translucent NS_AVAILABLE_IOS(3_0) UI_APPEARANCE_SELECTOR; 

//UINavigationBar上面不只是简单的显示标题，它也将标题进行了堆栈的管理，每一个标题抽象为的对象在iOS系统中是UINavigationItem对象，我们可以通过push与pop操作管理item组。
//向栈中添加一个item，上一个item会被推向导航栏的左侧，变为pop按钮，会有一个动画效果
- (void)pushNavigationItem:(UINavigationItem *)item animated:(BOOL)animated;
//pop一个item
- (nullable UINavigationItem *)popNavigationItemAnimated:(BOOL)animated; 
//当前push到最上层的item
@property(nullable, nonatomic,readonly,strong) UINavigationItem *topItem;
//仅次于最上层的item，一般式被推向导航栏左侧的item
@property(nullable, nonatomic,readonly,strong) UINavigationItem *backItem;
//获取堆栈中所有item的数组
@property(nullable,nonatomic,copy) NSArray<UINavigationItem *> *items;
//设置一组item
- (void)setItems:(nullable NSArray<UINavigationItem *> *)items animated:(BOOL)animated; 

//系统类型按钮文字颜色
@property(null_resettable, nonatomic,strong) UIColor *tintColor;

//通过barTintColor来设置背景色
@property(nullable, nonatomic,strong) UIColor *barTintColor NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;  

//设置工具栏背景和阴影图案
- (void)setBackgroundImage:(nullable UIImage *)backgroundImage forBarPosition:(UIBarPosition)barPosition barMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;
- (nullable UIImage *)backgroundImageForBarPosition:(UIBarPosition)barPosition barMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;

//通过背景图片来设置导航栏的外观
- (void)setBackgroundImage:(nullable UIImage *)backgroundImage forBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;

- (nullable UIImage *)backgroundImageForBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;

//背景阴影图片 - 即分割线
@property(nullable, nonatomic,strong) UIImage *shadowImage NS_AVAILABLE_IOS(6_0) UI_APPEARANCE_SELECTOR;

//标题的富文本
@property(nullable,nonatomic,copy) NSDictionary<NSString *,id> *titleTextAttributes NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;

//标题垂直偏移
- (void)setTitleVerticalPositionAdjustment:(CGFloat)adjustment forBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;

- (CGFloat)titleVerticalPositionAdjustmentForBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;

//设置返回按钮的图片
@property(nullable,nonatomic,strong) UIImage *backIndicatorImage NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;
@property(nullable,nonatomic,strong) UIImage *backIndicatorTransitionMaskImage NS_AVAILABLE_IOS(7_0) UI_APPEARANCE_SELECTOR;

@end

UINavigationBar是用于实现管理层级关系内容的组件，直接继承自UIView。通常用在UINavgationController类中，用于管理和显示UINavgationController的subViewController , 同时UINavgationBar也可以单独使用，添加至任何的UIView中。UINavigationBar比较重要的属性为，左侧按钮，中间的标题，以及右侧按钮。在平时的应用程序中，我们常常使用到自定义UINavigationBar来完成导航条的设置。

知识点1：导航栏全局属性设置

//全局设置导航栏主题
- (void)setNavigationControllerAppearance {
    [UINavigationBar appearance].barStyle  = UIBarStyleBlack;
    [[UINavigationBar appearance] setBarTintColor:[UIColor colorWithWhite:0.1 alpha:0.5]];
    [[UINavigationBar appearance] setTintColor:[UIColor whiteColor]];
}

全局设置导航栏的好处有两个：一是不用对每个NavigationBar进行设置；二是方便做主题管理，切换主题，只需要更改全局设置即可。

知识点2:自定义返回的图标并去除文字，要同时设置setBackIndicatorImage、setBackIndicatorTransitionMaskImage

[self.navigationController.navigationBar setBackIndicatorImage:[UIImage imageNamed:@"navibar_back_btn_bg_normal.png"]];  
  
[self.navigationController.navigationBar setBackIndicatorTransitionMaskImage:[UIImage imageNamed:@"navibar_back_btn_bg_normal.png"]];   
  
UIBarButtonItem *backItem = [[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStyleBordered target:nil action:nil];  

self.navigationItem.backBarButtonItem = backItem;  

知识点3：设置导航条底部线条的颜色

颜色转图片的代码：

@implementation UIImage (ColorImage)

+ (UIImage *)imageWithColor:(UIColor *)color
{
    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

@end


设置导航栏底部线条颜色的代码：

    UINavigationBar *navigationBar = self.navigationController.navigationBar;
    [navigationBar setBackgroundImage:[[UIImage alloc] init]
                       forBarPosition:UIBarPositionAny
                           barMetrics:UIBarMetricsDefault];
    //此处使底部线条颜色为红色
    [navigationBar setShadowImage:[UIImage imageWithColor:[UIColor redColor]]];

知识点4：隐藏导航条底部线条

//找查到Nav底部的黑线
- (UIImageView *)findHairlineImageViewUnder:(UIView *)view
{
    if ([view isKindOfClass:UIImageView.class] && view.bounds.size.height <= 1.0)
    {
        return (UIImageView *)view;
    }
    for (UIView *subview in view.subviews) {
        UIImageView *imageView = [self findHairlineImageViewUnder:subview];
        if (imageView) {
            return imageView;
        }
    }
    return nil;
}

然后设置这个UIImageView为隐藏就可以了；

方法二：这种主要是隐藏后没办法再显示出来

   UINavigationBar *navigationBar = self.navigationController.navigationBar;
    //设置透明的背景图，便于识别底部线条有没有被隐藏
    [navigationBar setBackgroundImage:[[UIImage alloc] init]
                       forBarPosition:UIBarPositionAny
                           barMetrics:UIBarMetricsDefault];
    //此处使底部线条失效
    [navigationBar setShadowImage:[UIImage new]];

六：关于UINavigationItem的定义

NS_CLASS_AVAILABLE_IOS(2_0) @interface UINavigationItem : NSObject <NSCoding>

- (instancetype)initWithTitle:(NSString *)title NS_DESIGNATED_INITIALIZER;

- (nullable instancetype)initWithCoder:(NSCoder *)coder NS_DESIGNATED_INITIALIZER;

//设置导航栏中间的内容标题
@property(nullable, nonatomic,copy)   NSString        *title;         
//设置导航栏中间的内容视图    
@property(nullable, nonatomic,strong) UIView          *titleView;        

@property(nullable,nonatomic,copy)   NSString *prompt;     
//返回
@property(nullable,nonatomic,strong) UIBarButtonItem *backBarButtonItem; 
//是否隐藏返回Button
@property(nonatomic,assign) BOOL hidesBackButton;

- (void)setHidesBackButton:(BOOL)hidesBackButton animated:(BOOL)animated;
//左边数组Item
@property(nullable,nonatomic,copy) NSArray<UIBarButtonItem *> *leftBarButtonItems NS_AVAILABLE_IOS(5_0);
//右边数组Item
@property(nullable,nonatomic,copy) NSArray<UIBarButtonItem *> *rightBarButtonItems NS_AVAILABLE_IOS(5_0);

- (void)setLeftBarButtonItems:(nullable NSArray<UIBarButtonItem *> *)items animated:(BOOL)animated NS_AVAILABLE_IOS(5_0);

- (void)setRightBarButtonItems:(nullable NSArray<UIBarButtonItem *> *)items animated:(BOOL)animated NS_AVAILABLE_IOS(5_0);

//通过指定该属性为YES，可以让leftBarButtonItem和backBarButtonItem同时显示，其中leftBarButtonItem显示在backBarButtonItem的右边 默认值为NO
@property(nonatomic) BOOL leftItemsSupplementBackButton NS_AVAILABLE_IOS(5_0);
//左边Item
@property(nullable, nonatomic,strong) UIBarButtonItem *leftBarButtonItem;
//右边Item
@property(nullable, nonatomic,strong) UIBarButtonItem *rightBarButtonItem;

- (void)setLeftBarButtonItem:(nullable UIBarButtonItem *)item animated:(BOOL)animated;

- (void)setRightBarButtonItem:(nullable UIBarButtonItem *)item animated:(BOOL)animated;

@end

UINavigationController会为每一个入栈的UIViewController生成一个UINavigationItem. UIViewController通过修改UINavigationItem可以控制UINavigationBar上的按钮和标题等

知识点1：关于UINavigationItem内容

你可以通过设置self.navigationItem.leftBarButtonItem为某个ButtonItem，
self.navigationItem.leftBarButtonItem
self.navigationItem.rightBarButtonItem
self.navigationItem.backBarButtonItem
self.navigationItem.titleView等等
注：1、这里的self 指的是UIViewController。
2、如果你在新视图中不修改backBarButtonItem 或leftBarButtonItem UINavigationController 会自动添加左边返回按钮用以返回了一个视图。总体的显示原则如下：
1）、Left side of the navigationBar 左按钮
a）如果当前的viewController设置了leftBarButtonItem，则显示当前VC所自带的leftBarButtonItem。
b）如果当前的viewController没有设置leftBarButtonItem，且当前VC不是rootVC的时候，则显示前一层VC的backBarButtonItem。如果前一层的VC没有显示的指定backBarButtonItem的话，系统将会根据前一层VC的title属性自动生成一个back按钮，并显示出来。
c）如果当前的viewController没有设置leftBarButtonItem，且当前VC已是rootVC的时候，左边将不显示任何东西。
此处注意：5.0中新增加了一个属性leftItemsSupplementBackButton，通过指定该属性为YES，可以让leftBarButtonItem和backBarButtonItem同时显示，其中leftBarButtonItem显示在backBarButtonItem的右边。
2)、title 标题
a）如果当前VC通过 .navigationItem.titleView指定了自定义的titleView，系统将会显示指定的titleView，此处要注意自定义titleView的高度不要超过navigationBar的高度，否则会显示出界。
b）如果当前VC没有指定titleView，系统则会根据当前VC的title或者当前VC的navigationItem.title的内容创建一个UILabel并显示，其中如果指定了navigationItem.title的话，则优先显示navigationItem.title的内容。
3)、Right side of the navigationBar  右按钮
a）如果当前VC指定了rightBarButtonItem的话，则显示指定的内容。
b）如果当前VC没有指定rightBarButtonItem的话，则不显示任何东西。

知识点2：相关属性运用

NavigationBar设置中间的标题或者自定义View
[self.navigationItem setTitle:@"旅行"];
[self.navigationItem setTitleView:[UIImage imageNamed:@"图片名称"];

单个或多个左右Item设置:单个leftItem设置:
UIBarButtonItem  *leftBarButton = [[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:@"BackIcon"] style:UIBarButtonItemStylePlain target:self action:nil];
 [leftBarButton setTintColor:[UIColor colorWithWhite:0 alpha:1]]; 
self.navigationItem.leftBarButtonItem = leftBarButton;

多个rightItem设置:
UIBarButtonItem *firstItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemReply target:self action:nil];
UIBarButtonItem *secondItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemTrash target:self action:nil];
NSArray *rightItems = @[firstItem, secondItem];
self.navigationItem.rightBarButtonItems = rightItems;

知识点3：设置偏移值

// 返回按钮内容左靠
button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
// 让返回按钮内容继续向左边偏移10
button.contentEdgeInsets = UIEdgeInsetsMake(0, -10, 0, 0);
viewController.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:button];

七：UIBarButtonItem定义内容

NS_CLASS_AVAILABLE_IOS(2_0) @interface UIBarButtonItem : UIBarItem <NSCoding>

- (instancetype)init NS_DESIGNATED_INITIALIZER;
//初始化
- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder NS_DESIGNATED_INITIALIZER;
- (instancetype)initWithImage:(nullable UIImage *)image style:(UIBarButtonItemStyle)style target:(nullable id)target action:(nullable SEL)action;
- (instancetype)initWithImage:(nullable UIImage *)image landscapeImagePhone:(nullable UIImage *)landscapeImagePhone style:(UIBarButtonItemStyle)style target:(nullable id)target action:(nullable SEL)action NS_AVAILABLE_IOS(5_0); 
- (instancetype)initWithTitle:(nullable NSString *)title style:(UIBarButtonItemStyle)style target:(nullable id)target action:(nullable SEL)action;
- (instancetype)initWithBarButtonSystemItem:(UIBarButtonSystemItem)systemItem target:(nullable id)target action:(nullable SEL)action;
//自定义视图
- (instancetype)initWithCustomView:(UIView *)customView;

//样式
@property(nonatomic)         UIBarButtonItemStyle style;            // default is UIBarButtonItemStylePlain
@property(nonatomic)         CGFloat              width;           
@property(nullable, nonatomic,copy)    NSSet<NSString *>   *possibleTitles;   // default is nil
//自定义视图
@property(nullable, nonatomic,strong)  __kindof UIView     *customView;       
@property(nullable, nonatomic)         SEL                  action;           // default is NULL
@property(nullable, nonatomic,weak)    id                   target;           // default is nil

- (void)setBackgroundImage:(nullable UIImage *)backgroundImage forState:(UIControlState)state barMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;
- (nullable UIImage *)backgroundImageForState:(UIControlState)state barMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;


- (void)setBackgroundImage:(nullable UIImage *)backgroundImage forState:(UIControlState)state style:(UIBarButtonItemStyle)style barMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(6_0) UI_APPEARANCE_SELECTOR;
- (nullable UIImage *)backgroundImageForState:(UIControlState)state style:(UIBarButtonItemStyle)style barMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(6_0) UI_APPEARANCE_SELECTOR;

@property(nullable, nonatomic,strong) UIColor *tintColor NS_AVAILABLE_IOS(5_0);


- (void)setBackgroundVerticalPositionAdjustment:(CGFloat)adjustment forBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR; 
- (CGFloat)backgroundVerticalPositionAdjustmentForBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;


- (void)setTitlePositionAdjustment:(UIOffset)adjustment forBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR; 
- (UIOffset)titlePositionAdjustmentForBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;

- (void)setBackButtonBackgroundImage:(nullable UIImage *)backgroundImage forState:(UIControlState)state barMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;
- (nullable UIImage *)backButtonBackgroundImageForState:(UIControlState)state barMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;

- (void)setBackButtonTitlePositionAdjustment:(UIOffset)adjustment forBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;
- (UIOffset)backButtonTitlePositionAdjustmentForBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;


- (void)setBackButtonBackgroundVerticalPositionAdjustment:(CGFloat)adjustment forBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;
- (CGFloat)backButtonBackgroundVerticalPositionAdjustmentForBarMetrics:(UIBarMetrics)barMetrics NS_AVAILABLE_IOS(5_0) UI_APPEARANCE_SELECTOR;

@end

知识点1：UIBarButtonSystemItem的样式介绍

typedef NS_ENUM(NSInteger, UIBarButtonSystemItem) {
    UIBarButtonSystemItemDone,//显示完成
    UIBarButtonSystemItemCancel,//显示取消
    UIBarButtonSystemItemEdit,  //显示编辑
    UIBarButtonSystemItemSave, //显示保存 
    UIBarButtonSystemItemAdd,//显示加号
    UIBarButtonSystemItemFlexibleSpace,//什么都不显示，占位一个空间位置
    UIBarButtonSystemItemFixedSpace,//和上一个类似
    UIBarButtonSystemItemCompose,//显示写入按钮
    UIBarButtonSystemItemReply,//显示循环按钮
    UIBarButtonSystemItemAction,//显示活动按钮
    UIBarButtonSystemItemOrganize,//显示组合按钮
    UIBarButtonSystemItemBookmarks,//显示图书按钮
    UIBarButtonSystemItemSearch,//显示查找按钮
    UIBarButtonSystemItemRefresh,//显示刷新按钮
    UIBarButtonSystemItemStop,//显示停止按钮
    UIBarButtonSystemItemCamera,//显示相机按钮
    UIBarButtonSystemItemTrash,//显示移除按钮
    UIBarButtonSystemItemPlay,//显示播放按钮
    UIBarButtonSystemItemPause,//显示暂停按钮
    UIBarButtonSystemItemRewind,//显示退后按钮
    UIBarButtonSystemItemFastForward,//显示前进按钮
    UIBarButtonSystemItemUndo,//显示消除按钮
    UIBarButtonSystemItemRedo ,//显示重做按钮
    UIBarButtonSystemItemPageCurl ,//在tool上有效
};

例如：

self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(right:)];


- (void)right:(id)sender
{
    NSLog(@"rightBarButtonItem");
}

知识点2：自定义UIView的UIBarButtonItem

 UIView *testView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 40, 60)];
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:testView];

最近有个妹子弄的一个关于扩大眼界跟内含的订阅号，每天都会更新一些深度内容，在这里如果你感兴趣也可以关注一下(嘿对美女跟知识感兴趣)，当然可以关注后输入：github 会有我的微信号，如果有问题你也可以在那找到我；当然不感兴趣无视此信息；