@C0deH4cker - Please accept my apologies. You are correct. I 100% missed that jpsilverberg was <b>not</b> attempting to do this from within Pythonista.
@jpsilverberg - C0deH4cker is correct (and this is what I touched on in part of my earlier commentary about 'single file'.)
As long as the Objective-C code you attempt to get python to call is compiled into the single application executable, you should be ok.
An example of this is the 'scene' python object in Pythonista. It's not pure python. It's a chunk of ObjC code that's compiled into the Pythonista core executable that exposes a python interface to interpreted scripts.
I haven't exported an Xcode project yet with Pythonista, so there's one thing I don't know which may possibly still be an issue:
If the Xcode project doesn't contain at least one .m / .c source file (with the Pythonista python interpreter as a static lib - or even more unlikely as pure source), you're going to be very hard pressed to find a place to insert your custom ObjC code into the final executable.