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.navigationBar setBackgroundImage:[UIImage imageNamed:@"navBack"] forBarMetrics:UIBarMetricsDefault];

        //   leftBarButtonItem  颜色

        self.navigationController.navigationBar.barStyle = UIStatusBarStyleDefault;

        [self.navigationController.navigationBar setTintColor:[UIColor whiteColor]];

        

        // nav title 颜色

        UIColor *color = [UIColor whiteColor];

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

        self.navigationController.navigationBar.titleTextAttributes = dic;

        

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

//        backItem.title = @"返回";

//        self.navigationItem.backBarButtonItem = backItem;