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Project Audit (Core Data)

Project Audit (Core Data)

Section titled “Project Audit (Core Data)”

Use this checklist to quickly discover how a project uses Core Data and which constraints apply (platform availability, CloudKit, history tracking, etc.).

Determine platform constraints

Section titled “Determine platform constraints”
  • Find the deployment target (iOS/macOS version). Many recommendations depend on this (e.g. staged migration and composite attributes require iOS 17+/macOS 14+).
  • Note whether the project is Swift 6 / strict concurrency enabled (Sendable and isolation warnings change the advice).

Inspect the data model

Section titled “Inspect the data model”
  • Open the model XML (*.xcdatamodeld/*/contents) and check:
    • entities, attributes, relationships, constraints
    • versioning setup (multiple model versions)
    • renaming identifiers (for lightweight migration)
    • composite attributes (iOS 17+)

Identify stack setup

Section titled “Identify stack setup”

Search for:

  • NSPersistentContainer vs NSPersistentCloudKitContainer
  • loadPersistentStores configuration
  • persistentStoreDescriptions (migration options, history tracking, CloudKit options)
  • viewContext configuration (merge policy, automaticallyMergesChangesFromParent, query generations)
  • background context creation (newBackgroundContext, performBackgroundTask)

Then consult:

  • stack-setup.md for recommended defaults and merge policies
  • cloudkit-integration.md if CloudKit is enabled

Check for persistent history tracking (required for some flows)

Section titled “Check for persistent history tracking (required for some flows)”

Search for:

  • NSPersistentHistoryTrackingKey
  • NSPersistentStoreRemoteChangeNotificationPostOptionKey
  • remote change notifications and history processing/merging

Then consult:

  • persistent-history.md for the Observer/Fetcher/Merger/Cleaner pattern

Spot risky concurrency patterns

Section titled “Spot risky concurrency patterns”

Search for:

  • cross-thread access to managed objects (look for passing NSManagedObject into async tasks/closures)
  • performAndWait usage (risk of deadlocks / UI blocking)
  • @unchecked Sendable applied to Core Data types (usually hides a real problem)

Then consult:

  • threading.md and concurrency.md

Useful debugging flags (for repro builds only)

Section titled “Useful debugging flags (for repro builds only)”
  • -com.apple.CoreData.ConcurrencyDebug 1 (threading violations)
  • -com.apple.CoreData.SQLDebug 1 (SQL logging)