HealthKit Code Review

Quick Reference

Issue Type Reference

HKHealthStore, permissions, status checks, privacy references/authorization.md

HKQuery types, predicates, anchored queries, statistics references/queries.md

Background delivery, observer queries, completion handlers references/background.md

HKQuantityType, HKCategoryType, workouts, units references/data-types.md

Review Checklist

• HKHealthStore.isHealthDataAvailable() called before any HealthKit operations

• Authorization requested only for needed data types (minimal permissions)

• requestAuthorization completion handler not misinterpreted as permission granted

• No attempt to determine read permission status (privacy by design)

• Query results dispatched to main thread for UI updates

• HKObjectQueryNoLimit used only with bounded predicates

• HKStatisticsQuery used for aggregations instead of manual summing

• Observer query completionHandler() always called (use defer )

• Background delivery registered in application(_:didFinishLaunchingWithOptions:)

• Background delivery entitlement added (iOS 15+)

• Correct units used for quantity types (e.g., count/min for heart rate)

• Long-running queries stored as properties and stopped in deinit

When to Load References

• Reviewing authorization/permissions flow -> authorization.md

• Reviewing HKSampleQuery, HKAnchoredObjectQuery, or predicates -> queries.md

• Reviewing HKObserverQuery or enableBackgroundDelivery -> background.md

• Reviewing HKQuantityType, HKCategoryType, or HKWorkout -> data-types.md

Review Questions

• Is isHealthDataAvailable() checked before creating HKHealthStore?

• Does the code gracefully handle denied permissions (empty results)?

• Are observer query completion handlers called in all code paths?

• Is work in background handlers minimal (~15 second limit)?

• Are HKQueryAnchors persisted per sample type (not shared)?