相关疑难解决方法(0)

我无法正确设置自定义后退指示图像.指标不居中!

这是一张照片:

我在didFinishLaunchingWithOptions:方法中设置指标图像......

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

   UIImage *image = [UIImage imageNamed:@"Back"];
   [UINavigationBar appearance].backIndicatorImage = image;
   [UINavigationBar appearance].backIndicatorTransitionMaskImage = image;

   return YES;
}

我该如何居中呢？

ps我已经在iOS 7中读过这个自定义后退指示器图像而不是垂直居中,但实际上它对我不起作用.