An introduction to PyObjC describes the general method for translating Objective-C calls into Python calls, including the handling of pass-by-reference arguments and buffers.
This document describes where the PyObjC bindings for this framework are different from the general rule, such as mentioning APIs that are not supported or where the interface is different than expected.
This framework is provided as is, the wrapping is not tested at all at the moment and due to it’s low-level nature there it is expected that there issues with these bindings.