iOS系统导航栏中有leftBarButtonItem和rightBarButtonItem，我们可以根据自己的需求来自定义这两个UIBarButtonItem。

四种创建方法

系统提供了四种创建的方法：
代码如下：

- (instancetype)initWithBarButtonSystemItem:(UIBarButtonSystemItem)systemItem target:(id)target action:(SEL)action;

- (instancetype)initWithImage:(UIImage *)image style:(UIBarButtonItemStyle)style target:(id)target action:(SEL)action;

- (instancetype)initWithTitle:(NSString *)title style:(UIBarButtonItemStyle)style target:(id)target action:(SEL)action;

- (instancetype)initWithBarButtonSystemItem:(UIBarButtonSystemItem)systemItem target:(id)target action:(SEL)action;

- (instancetype)initWithCustomView:(UIView *)customView;

通过系统UIBarButtonSystemItem创建

自定义rightBarButtonItem，代码如下：
代码如下：

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

UIBarButtonSystemItem有以下样式可以供选择：
代码如下：

typedef NS_ENUM(NSInteger, UIBarButtonSystemItem) {
    UIBarButtonSystemItemDone,
    UIBarButtonSystemItemCancel,
    UIBarButtonSystemItemEdit, 
    UIBarButtonSystemItemSave, 
    UIBarButtonSystemItemAdd,
    UIBarButtonSystemItemFlexibleSpace,
    UIBarButtonSystemItemFixedSpace,
    UIBarButtonSystemItemCompose,
    UIBarButtonSystemItemReply,
    UIBarButtonSystemItemAction,
    UIBarButtonSystemItemOrganize,
    UIBarButtonSystemItemBookmarks,
    UIBarButtonSystemItemSearch,
    UIBarButtonSystemItemRefresh,
    UIBarButtonSystemItemStop,
    UIBarButtonSystemItemCamera,
    UIBarButtonSystemItemTrash,
    UIBarButtonSystemItemPlay,
    UIBarButtonSystemItemPause,
    UIBarButtonSystemItemRewind,
    UIBarButtonSystemItemFastForward,
#if __IPHONE_3_0 <= __IPHONE_OS_VERSION_MAX_ALLOWED
    UIBarButtonSystemItemUndo,
    UIBarButtonSystemItemRedo,
#endif
#if __IPHONE_4_0 <= __IPHONE_OS_VERSION_MAX_ALLOWED
    UIBarButtonSystemItemPageCurl,
#endif
};

最后别忘了实现right:方法：
代码如下：

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

自定义文字的UIBarButtonItem

self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"back" style:UIBarButtonItemStylePlain target:self action:@selector(back:)];
UIBarButtonItemStyle有以下三种选择：
代码如下：

typedef NS_ENUM(NSInteger, UIBarButtonItemStyle) {
    UIBarButtonItemStylePlain,
    UIBarButtonItemStyleBordered NS_ENUM_DEPRECATED_IOS(2_0, 8_0, "Use UIBarButtonItemStylePlain when minimum deployment target is iOS7 or later"),
    UIBarButtonItemStyleDone,
};

实现back:方法：
代码如下：

- (void)back:(id)sender
{
    [self.navigationController popViewControllerAnimated:YES];
}

自定义照片的UIBarButtonItem
代码如下：

self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"test"] style:UIBarButtonItemStylePlain target:self action:@selector(right:)];

自定义UIView的UIBarButtonItem

自定义UIView，然后通过initWithCustomView:方法来创建UIBarButtonItem。
代码如下：

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

看到有朋友在后台提问：

我现在即需要改那个导航原生的返回图片，也要改返回文字，应该怎么改呢，求指教。
其实，这个就可以用initWithCustomView:来解决，自定义UIView你可以放UIImageView和UILabel。可以自定义UIView，那么想怎么定义都是可以的。

下面来看一个有趣的例子：
先说一下需求：
1.做一个RightBarButtonItem不断旋转的Demo；
2.点击RightBarButtonItem 按钮旋转或暂停；
最终效果展示：

就是那个音符图形的旋转。
关键代码展示（已加注释）：
代码如下：

//
// ViewController.m
// NavigationBtn
//

#import "ViewController.h"
#define DEGREES_TO_RADIANS(angle) ((angle) / 180.0 * M_PI)

///ImageView旋转状态枚举
typedef enum {
RotateStateStop,
RotateStateRunning,
}RotateState;

@interface ViewController ()
{
///旋转角度
CGFloat imageviewAngle;
///旋转ImageView
UIImageView *imageView;
///旋转状态
RotateState rotateState;
}

@end

代码如下：

@implementation ViewController

- (void)viewDidLoad
{
[super viewDidLoad];
self.title=@"微信公众账号:乐Coding";
[self buildBarButtonItem];
}
#pragma mark 添加 RightBarButtonItem
-(void)buildBarButtonItem{

imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"icon"]];
imageView.autoresizingMask = UIViewAutoresizingNone;
imageView.contentMode = UIViewContentModeScaleToFill;
imageView.bounds=CGRectMake(0, 0, 40, 40);
//设置视图为圆形
imageView.layer.masksToBounds=YES;
imageView.layer.cornerRadius=20.f;
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.frame = CGRectMake(0, 0, 40, 40);
[button addSubview:imageView];
[button addTarget:self action:@selector(animate) forControlEvents:UIControlEventTouchUpInside];
imageView.center = button.center;
//设置RightBarButtonItem
UIBarButtonItem *barItem = [[UIBarButtonItem alloc] initWithCustomView:button];
self.navigationItem.rightBarButtonItem = barItem;
}
#pragma mark 点击 RightBarButtonItem
- (void)animate {
//改变ImageView旋转状态
if (rotateState==RotateStateStop) {
rotateState=RotateStateRunning;
[self rotateAnimate];
}else{
rotateState=RotateStateStop;
}
}
#pragma mark 旋转动画
-(void)rotateAnimate{
imageviewAngle+=50;
//0.5秒旋转50度
[UIView animateWithDuration:0.5 delay:0.0 options:UIViewAnimationOptionCurveLinear animations:^{
imageView.transform = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(imageviewAngle));
} completion:^(BOOL finished) {
if (rotateState==RotateStateRunning) {
[self rotateAnimate];
}
}];
}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

@end