The summary.
CHECK AVAILABILITY, ENTITLEMENTS AND CONSENT BEFORE BUILDING ON ANY FRAMEWORK
Some capabilities require approval Apple grants selectively, and discovering that late is expensive.
USE THE SYSTEM PICKER WHERE IT SUFFICES
It requires no camera or library permission at all. And support limited photograph selection — many users choose it.
RESPECT THE EXPENSIVE-CONNECTION SIGNAL
Path monitoring tells you when the user is on metered data. Defer large transfers, because users notice consumption.
REQUEST THE LOWEST LOCATION ACCURACY THAT WORKS, AND ONLY WHILE IN USE
Requesting always-on immediately is refused, and review scrutinises it. Stop sensor updates when not needed.
TEST DATA MIGRATION FROM THE RELEASED VERSION BEFORE EVERY SUBMISSION
An unhandled model change loses user data or crashes on launch.
ON-DEVICE INTELLIGENCE COSTS NO DATA AND WORKS OFFLINE
But test accuracy on data resembling your actual users — models trained elsewhere perform differently on local names, languages and documents.
VERIFY EVERY PURCHASE SERVER-SIDE
Client-side verification is trivially bypassed.
