I'd like my (currently) closed-source iOS app to use some GPLv2 licensed code. The code I want to use is simply a converter from one file format to another — nothing too complex or proprietary. Given the restrictions imposed by the GPL, I understand that I cannot integrate the GPL-licensed code directly into my app. However, would I be in the clear if I modify the GPL'd code to run as a separate process from inside my app (perhaps via XPC) and then publicly release those modifications? (This previous answer implies that I can. This answer urges caution, but I can easily imagine somebody using this converter outside of my closed-source app.)
Additionally, would I be allowed to distribute a complied binary of this code along with my app? Users wouldn't be able to switch out this binary while running my app because of signing restrictions, but I'm not sure how this changes given
a) the more lax approach of the GPLv2 to Tivoization, and
b) the fact that Apple now allows anyone to create a free developer account and compile apps for their iDevices, thus permitting a form of side-loading.