Not so much on the device itself, but there is a lot of baggage around the iOS workflow, imposed by Apple. You have to pay Apple $99/year, set up provisioning profiles, and fiddle with code signing when doing deployment. It was a gigantic hassle when I was first starting out a few years ago, maybe the onboarding has gotten better since then. I still run into those problems sometimes, mostly when trying to distribute in a non-standard way (eg, OTA outside the app store, ad hoc distribution, etc). And it gets more complicated from there if you're part of an organization that has more than a single, trivial app or separate groups of developers, testers, etc.
None of this is specific to OCaml on iOS, though -- you have to go through all that even with Objective-C. When testing in the simulator, all that can be bypassed as well.