I don't know what IDE you're using but doxygen lets you generate documentation from comments in Objective-C (as well as C, C++, Java, and some others).
If you're using Xcode (just assuming, since you're using Objective-C), there does seem to be some level of integration (not tested by me, just found on Google): http://developer.apple.com/tools/creatingdocsetswithdoxygen.html
