+(instancetype)itemWithImage:(NSString *)image highimage:(NSString *)highimage target:(id)target action:(SEL)action
{UIButton *Btn = [[UIButton alloc]init];[Btn setBackgroundImage:[UIImage imageNamed:image] forState:UIControlStateNormal];[Btn setBackgroundImage:[UIImage imageNamed:highimage] forState:UIControlStateHighlighted];[Btn addTarget:target action:action forControlEvents:UIControlEventTouchUpInside];Btn.size = Btn.currentBackgroundImage.size;return [[self alloc]initWithCustomView:Btn];
}

/*** 可以在这个方法中拦截所有push进来的控制器*/
- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{if (self.childViewControllers.count > 0) {// 如果push进来的不是第一个控制器UIButton *backBtn = [UIButton buttonWithType:UIButtonTypeCustom];[backBtn setTitle:@"返回" forState:UIControlStateNormal];[backBtn setImage:[UIImage imageNamed:@"navigationButtonReturn"] forState:UIControlStateNormal];[backBtn setImage:[UIImage imageNamed:@"navigationButtonReturnClick"] forState:UIControlStateHighlighted];backBtn.size = CGSizeMake(70, 30);// 让按钮内部的所有内容左对齐backBtn.contentEdgeInsets = UIEdgeInsetsMake(0, -50, 0, 0);[backBtn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];[backBtn setTitleColor:[UIColor redColor] forState:UIControlStateHighlighted];[backBtn addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside];viewController.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithCustomView:backBtn];// 隐藏tabbarviewController.hidesBottomBarWhenPushed = YES;}// 这句super的push要放在后面，让view controller可以覆盖在上面leftbarbuttonitem
    [super pushViewController:viewController animated:animated];}

/*** 当第一次使用这个类的时候会调用一次*/
+ (void)initialize
{// 当导航栏用在XMGNavigationController中, appearance设置才会生效//    UINavigationBar *bar = [UINavigationBar appearanceWhenContainedIn:[self class], nil];// 视情况而定UINavigationBar *bar = [UINavigationBar appearance];[bar setBackgroundImage:[UIImage imageNamed:@"navigationbarBackgroundWhite"] forBarMetrics:UIBarMetricsDefault];
}