you should do a search in this forum (and Google or preferred Internet search engine) for what I guess you are actually asking
using iPhone camera as video (and microphone?) source in OBS. Right?
Lots of ways from USB connection and certain s/w, to NDI and more. There are article out there comparing the different options, as there are free and pay options, but some of the free ones aren't worth it.. OBS is great, but not all FOSS is of similar quality (and some is just obscured malware).. ymmv
First, decide which features are must have vs nice to have
Then to decide how much your time is worth (troubleshooting/setup)
and how important reliability is?
in general - a wired connection (USB in this case) will almost always be more reliable than a WiFi one. but iOS walled garden causes its own 'considerations' [hassles].
