Porting an existing Cocoa class to build in iPhone

I just wanted to know if anyone had experience with porting an existing class written in Cocoa for a Mac --> Cocoa Touch and other iPhone frameworks.

Currently I am interested in porting AsyncSocket (open source project) to build on the iPhone. Here is a link to the project: http://code.google.com/p/cocoaasyncsocket/

Aside from rewriting each method, is there a general technique I could follow to do this sort of thing?