Macros for Designing by Contract in Objective-C simplifies the process of using the Design by Contract software methodology invented and pushed by Bertrand Meyer. This involves creating a "contract" for each Object in your program that explicitly states the input and output ranges that the Object expects. The macros implement the pre- and post-assertions as well as invariants and references to "old" variables (the state of the variable before entering a method).
Netclasses is an asynchronous networking library that works with GNUstep and Mac OS X. Out of the box, it gives a nice, asynchronous, and object-oriented interface for IRC, line- based, and raw TCP/IP connections. Users can easily subclass the raw TCP/IP or line-based interfaces to create asynchronous interfaces for other sorts of connections.
SMS Framework is an Objective C framework for decoding SMS messages in PDU format to objects. It is easily usable in Cocoa and GNUstep environments, and it reduces developer responsibility for decoding messages to extracting the raw messages from the phone. The XCode project file contains three targets: one system wide framework, one framework to include in applications, and a small application for testing the framework.