How to arrange files within Xcode application groups?

In X code, I 开发者_Go百科have added 3 groups named

* Classes
* COCOS2d
* Images

Under images, I have added 40 files. But all images under IMAGEs group aren't sorted by name.

I want to sort them, but I didn't found any option.

Select all the images in the group tree under your images group, then choose Edit > Sort > By Name from the menu.