Ios7 如何使用UIappearance在根viewcontroller中获取透明导航栏

在我的应用程序的委托中，我指定了一个透明的工具栏（如问题18969248的答案所示）：-
代码是：

UINavigationBar *navigationBarAppearance = [UINavigationBar appearance];
navigationBarAppearance.backgroundColor = [UIColor clearColor];
[navigationBarAppearance setBackgroundImage:[[UIImage alloc] init] forBarMetrics:UIBarMetricsDefault];
navigationBarAppearance.shadowImage = [[UIImage alloc] init];
navigationController = [[UINavigationController alloc] initWithRootViewController:viewController];

这适用于推送到导航控制器堆栈上的所有视图控制器，但不适用于根视图控制器（从NIB加载）。

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如何在根视图控制器的导航栏中获得透明度？

如果您使用的是故事板，可能应该通过AppDelegate以编程方式加载根视图控制器：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{

    UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"yourStoryboard"
                                                             bundle: nil];
    YourCustomRootViewController *customRootVC = (YourCustomRootViewController*) [mainStoryboard instantiateViewControllerWithIdentifier:@"firstAddProductViewController"];

    // If you're not using storyboard, simply instantiate it this way
    YourCustomRootViewController *customRootVC = [[YourCustomRootViewController alloc] initWithNibName:@"yourNib" bundle:nil];

    /* In here, you want to add the code relative to the navigation bar of your rootVC */
    [self.window setRootViewController:customRootVC];

}