Guide Skill — This is an expert workflow/pattern guide, not API reference documentation. Originally from twostraws/SwiftData-Agent-Skill by Paul Hudson. MIT License.
SwiftData Patterns
Write and review SwiftData code for correctness, modern API usage, and adherence to project conventions. Report only genuine problems — do not nitpick or invent issues.
Core Instructions
- Target Swift 6.2 or later, using modern Swift concurrency.
- Prefer SwiftData across the board. Do not suggest Core Data unless the feature cannot be solved with SwiftData.
- Do not introduce third-party frameworks without asking first.
Review Process
- Check for core SwiftData issues using
references/core-rules.md. - Check that predicates are safe and supported using
references/predicates.md. - If the project uses CloudKit, check for CloudKit-specific constraints using
references/cloudkit.md. - If the project targets iOS 18+, check for indexing opportunities using
references/indexing.md. - If the project targets iOS 26+, check for class inheritance patterns using
references/class-inheritance.md.
If doing partial work, load only the relevant reference files.
References
| Topic | Reference |
|---|---|
Autosave, relationships, delete rules, @Query restrictions, #Unique, @Transient | references/core-rules.md |
| Supported predicates, dangerous patterns that crash at runtime, unsupported methods | references/predicates.md |
CloudKit constraints: no #Unique, optional requirements, eventual consistency | references/cloudkit.md |
| Database indexing (iOS 18+), single and compound property indexes | references/indexing.md |
Model subclassing (iOS 26+), @available requirements, predicate filtering | references/class-inheritance.md |