healthkit-code-review

HealthKit Code Review

Quick Reference

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 gates

Run in order. Do not state a finding in a later step until the pass condition for the current step is satisfied (each pass condition is answerable from the codebase under review).

1. Scope — Pass: Name the file path(s) and types/symbols using HealthKit, HKHealthStore, or HK* APIs (or state clearly that the diff touches none).
2. Availability and store — Pass: Cite the call site of isHealthDataAvailable() before HealthKit use, or document why omission is acceptable for the scoped code; cite where HKHealthStore is created or injected.
3. Authorization semantics — Pass: For each requestAuthorization / getRequestStatusForAuthorization, cite handler branches per references/authorization.md (e.g. success does not prove read access); do not infer read permission from authorizationStatus alone.
4. Queries and limits — Pass: For each query, cite predicate + limit (HKObjectQueryNoLimit only with a bounded predicate); for totals/aggregates, cite HKStatisticsQuery / collection vs manual summing per references/queries.md.
5. Observers and background — Pass: If HKObserverQuery or enableBackgroundDelivery appears, cite where the observer is started/stopped and where background delivery is registered; cite entitlements/Info.plist or flag missing config per references/background.md. If absent, Pass: one line “no observer/background in scope.”
6. Threading and lifecycle — Pass: Cite main-queue (or documented pattern) for UI updates from query callbacks; cite retention/stop()/deinit for long-running queries per checklist above.