设置 BackButtonBackgroundImage 通过 UIAppearance 目前在iOS 7中有一些奇怪的行为。这可能与更新的设计有关，它将rect-style按钮替换为backIndicatorImage（箭头）。

Setting BackButtonBackgroundImage via UIAppearance currently has some odd behavior in iOS 7. This is probably related to the updated design, which replaces the rect-style button with a backIndicatorImage (an arrow).

这留下了3个用于自定义后退按钮外观的选项：

This leaves 3 options for customizing the back button's appearance:

1. 通过设置 UINavigationBar （或其中一个超类）的c $ c> tintColor 属性。

1. Change the color of the backIndicatorImage by setting the tintColor property on UINavigationBar (or one of its superclasses).

在 UINavigationBar 上设置新的 backIndicatorImage 属性>到自定义图像。 （不要忘记设置 backIndicatorTransitionMaskImage ，否则它将无效）

Set the new backIndicatorImage property on UINavigationBar to a custom image. (don't forget to set the backIndicatorTransitionMaskImage as well or it won't work)

创建自定义 UIBarButtonItem 并手动将其指定为 UINavigationItem 的 leftBarButtonItem 。 （参见上面提到的答案 Mashhadi ）

Create a custom UIBarButtonItem and manually assign it as UINavigationItem's leftBarButtonItem. (See the answer mentioned above by Mashhadi)