Cocoa Bindings
The basic concept for the Cocoa client is to wrap up a context and associated structures in a class (ContextInterface.h) then maintain a representation of the current context external to this class, to make it easier to update the interface as the context processes sockets. This takes the form of an NSArray of NSDictionaries, one dictionary per torrent.
I’ve had it in the back of my mind to convert the GUI over to using bindings instead of delegate / datasource methods, and now that the current svn code has a rudimentary level of state display (via stdout piping to a textview), I’m busy refactoring the code to use bindings.
There’s a very useful tutorial over at CocoaDevCentral which teaches the essentials of bindings, and makes understanding the class documentation much easier.