Here's a article I thought you guys would like: http://www.onlamp.com/pub/a/onlamp/...-apis-apple-didnt-want-you-to-know-about.html "With the release of Apple's SDK for building iPhone applications, many have plunged head-first into this new platform for the first time, with the new-found excitement that comes in discovering something entirely new and innovative. The energy surrounding the iPhone has been building steadily since its release last June, and Apple's initial "beta" offering of their SDK gave developers many of the tools they needed to get engaged. Within a short time, however, the community hit a brick wall in many respects, leaving many disenchanted by the restrictions imposed on developers. While Apple insists that the SDK provides the same tools used to create their own software, developers have found that they don't have access to the same low-level functions of the iPhone, such as the ability to run applications in the background, build certain types of objects, or use low-level frameworks such as CoreSurface, Celestial, or LayerKit — all of which provide direct access to graphics and sound components. These, along with many other features, are found in Apple's own applications, but nowhere to be found in the SDK." "Back to the present, the APIs available in the Apple SDK are useful for building your average game, or your average application, but very lacking for building applications with more sophisticated, low-level requirements. Fortunately, there is another set of interfaces that Apple never wanted you to know about, the "real" set of APIs that Apple uses. These are the same interfaces that have been made available through the unofficial SDK "tool chain," only we didn't know it at the time. The great news is that you can use the Apple SDK (via XCode) to build applications using these hidden APIs, and this article will show you how." "Now for the fun part, for those who are, or will soon be running the "Aspen" software on their iPhone, and would like to build applications using these hidden APIs, there are now two different methods you can use: the open source tool chain or Apple's official SDK (with some customizations). Using either, it is possible to not only write applications that take full advantage of the low-level frameworks used by Apple's own software, but also to build existing applications written for the open source tool chain." "Apple's low-level APIs, made available in the open tool chain, contain some objects and methods that have been intentionally left out of the Apple SDK, to help control what developers can and can't do. If you think about the ramifications of what it would mean to be able to write your own movie player, for example, it would be very unwise for Apple to foster applications that competed with their own. Introducing our first example of a missing framework, the CoreSurface framework. CoreSurface allows for direct writes to a screen surface, making applications such as custom movie players and software emulators possible. The framework itself is included with the iPhone and the Apple SDK, as it is used by higher-level libraries such as OpenGL, but developers cannot take advantage of it because the framework headers are missing. Another example is in a missing set of objects named UIPreferencesTable, used for building settings screens inside an application. Apple's document insists that you create a preference bundle for your application, so that users have to exit your program and use the "Settings" application. This all caters to look-and-feel, but some find it unreasonable, and equate removing this object as removing the ability for a desktop program to have a "Preferences" menu option. To take advantage of these hidden APIs within the Apple SDK, you'll need to install the header files for these objects and then modify your XCode projects to use them. An unauthorized set of private headers is being maintained by a group of software developers named "the iPhone Dev Team." Unofficial, these headers are used by the open source SDK. To download and install these low-level APIs, do the following from a Terminal window on your desktop:" The article has the rest.