SwiftData Code Review

Quick Reference

Review Checklist

• Models marked final (subclassing crashes)
• @Relationship decorator on ONE side only (not both)
• Delete rules explicitly set (not relying on default .nullify)
• Relationships initialized to empty arrays, not default objects
• Batch operations used for bulk inserts (append(contentsOf:))
• @Query not loading thousands of items on main thread
• External values in predicates captured in local variables
• Scalar comparisons in predicates (not object references)
• @ModelActor used for background operations
• PersistentIdentifier/DTOs used to pass data between actors
• VersionedSchema defined for each shipped version
• MigrationPlan passed to ModelContainer

When to Load References

• Reviewing @Model or relationships -> model-design.md
• Reviewing @Query or #Predicate -> queries.md
• Reviewing @ModelActor or background work -> concurrency.md
• Reviewing schema changes or migrations -> migrations.md

Review Questions

1. Could this relationship assignment cause NULL foreign keys?
2. Is @Relationship on both sides creating circular references?
3. Could this @Query block the main thread with large datasets?
4. Are model objects being passed between actors unsafely?
5. Would schema changes require a migration plan?