I'm not able to get this to work. Any chance someone could post some sample code?

OR, save each data point in its own record

Yep, device itself will reduce CPU speed in high heat conditions, affecting overall device performance. You can check thermal state via NSProcessInfo https://developer.apple.com/documentation/foundation/nsprocessinfo/1417480-thermalstate

for second bullet point above, transfer is only required if you've shipped the app, otherwise, it can be built using a new bundle ID that is defined under your developer account. also, for future reference, consult an intellectual property attorney and draft an "work-for-hire" contract.

its been a while since I wrote my MusicPlayer code, but at one point, I had to move all the calls into the main thread… fwiw