navbarButtonItem一些小技巧

导航栏右边按钮：颜色

info.plist 添加  View controller-based status bar appearance，  设置为NO，

[self.navigationController.navigationBarsetBackgroundImage:[UIImageimageNamed:@"navBack"]forBarMetrics:UIBarMetricsDefault];

        //   leftBarButtonItem 颜色

        self.navigationController.navigationBar.barStyle = UIStatusBarStyleDefault;

        [self.navigationController.navigationBarsetTintColor:[UIColorwhiteColor]];

        

        // nav title 颜色

        UIColor *color = [UIColorwhiteColor];

        NSDictionary *dic = [NSDictionarydictionaryWithObject:color  forKey:NSForegroundColorAttributeName];

        self.navigationController.navigationBar.titleTextAttributes = dic;

        

//        UIBarButtonItem *backItem = [[UIBarButtonItem alloc] init];

//        backItem.title = @"返回";

//        self.navigationItem.backBarButtonItem = backItem;