I am building a training app for endurance athletes and I am trying to get the storage design right before I write it. Guideline 5.1.3(ii) says an app "may not store personal health information in iCloud", but I cannot find anywhere that defines what falls under that phrase, and the HealthKit documentation does not mention iCloud at all.
The app records workouts from Bluetooth sensors (power, speed, distance, elevation, GPS, heart rate). With permission it also reads HRV, resting heart rate and sleep from HealthKit, and calculates a daily readiness value from them. I would like to keep the app's own records in my own CloudKit container so the user sees them on their iPad.
Three things I cannot resolve from the documentation:
Is a developer's own CloudKit container — private or shared database — "iCloud" for the purposes of 5.1.3(ii)? Does 5.1.3(ii) apply to physiological data the app measures itself from a Bluetooth sensor and never writes to HealthKit — for instance heart rate during a workout? Is a value derived from HealthKit samples, such as a readiness score computed from HRV, resting heart rate and sleep, "personal health information" even though it is not itself a HealthKit sample?
I am aware that HealthKit already syncs a user's own data across their devices, so I do not intend to mirror HealthKit samples. My question is about the app's own records and derived values.
Any pointer to documentation I have missed would be very welcome.