I am developing an iPhone app and have to parse xml files in order to put them into a database. I will also be using those same xml parsers in my app so users can import their o
Create a static library project, then use the interproject dependency feature of Xcode to build them in the correct order and link the app with the static library. You'll need to have a common build directory set for all the projects for this to work correctly (at least you did around Xcode 3.0, didn't check if this is still a problem with 3.1).
You can set the build directory from the target or project's build settings (in the Get Info pane). To create an interpoject dependency:
Sounds more complicated than it is. It isn't much.
(Small extras: yes, you need a common build folder as indicated in the Xcode Project Management Guide, and the Xcode Build System Guide can help you "get" Xcode's build system, which -- at the cost of starting a religion war -- I think is one of the most flexible and simple build systems out there.)