# AIFitnessAPI — September 2026

Fitness and health API news for September 2026: 24 pages verified, across 2 sections.

## Pages published or re-verified

**Build Guides** (14)

- [How to Build a Kids Fitness App (2026)](https://aifitnessapi.com/build/kids-fitness-app)
- [How to Build a Triathlon App (2026)](https://aifitnessapi.com/build/triathlon-app)
- [How to Build a HIIT App (2026)](https://aifitnessapi.com/build/hiit-app)
- [How to Build a Hiking App (2026)](https://aifitnessapi.com/build/hiking-app)
- [How to Build a Swimming App (2026)](https://aifitnessapi.com/build/swimming-app)
- [How to Build a Cycling App (2026)](https://aifitnessapi.com/build/cycling-app)
- [How to Build a Senior Fitness App (2026)](https://aifitnessapi.com/build/senior-fitness-app)
- [How to Build a Step Challenge App (2026)](https://aifitnessapi.com/build/step-challenge-app)
- [How to Build a Cycle Tracking App (2026)](https://aifitnessapi.com/build/cycle-tracking-app)
- [How to Build a Meditation App (2026)](https://aifitnessapi.com/build/meditation-app)
- [How to Build a Recovery App (2026)](https://aifitnessapi.com/build/recovery-app)
- [How to Build a Sleep Tracking App (2026)](https://aifitnessapi.com/build/sleep-tracking-app)
- [How to Build a Meal Planning App (2026)](https://aifitnessapi.com/build/meal-planning-app)
- [How to Build a Weight Loss App (2026)](https://aifitnessapi.com/build/weight-loss-app)

**Troubleshooting** (10)

- [Undocumented HealthKit Errors: Handling a Case Apple Never Described](https://aifitnessapi.com/fix/healthkit-undocumented-errors)
- [HealthKit errorNotPermissibleForGuestUserMode: Writes Blocked in a Guest Session](https://aifitnessapi.com/fix/healthkit-guest-user-mode)
- [HealthKit Workout Session Errors: Four Cases, Two of Them Undocumented](https://aifitnessapi.com/fix/healthkit-workout-session-errors)
- [HealthKit errorRequiredAuthorizationDenied: Clinical Records Are a Separate Class](https://aifitnessapi.com/fix/healthkit-required-authorization-denied)
- [HealthKit errorAuthorizationNotDetermined: You Called Before You Asked](https://aifitnessapi.com/fix/healthkit-authorization-not-determined)
- [HealthKit errorInvalidArgument: Finding the Argument HealthKit Rejected](https://aifitnessapi.com/fix/healthkit-invalid-argument)
- [HealthKit errorNoData: The Query Ran and Found Nothing](https://aifitnessapi.com/fix/healthkit-error-no-data)
- [HealthKit errorHealthDataRestricted: An MDM Profile Turned HealthKit Off](https://aifitnessapi.com/fix/healthkit-data-restricted-mdm)
- [HealthKit errorHealthDataUnavailable: The Device Does Not Support HealthKit](https://aifitnessapi.com/fix/healthkit-health-data-unavailable)
- [HealthKit errorDatabaseInaccessible: Reads Fail While the Device Is Locked](https://aifitnessapi.com/fix/healthkit-database-inaccessible)

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Every claim traces to a primary source checked on the review date. How we verify: https://aifitnessapi.com/methodology
This digest is generated from the changes tracker and the pages themselves, so it cannot describe work that did not happen.