---
name: guide-swiftdata
description: SwiftData patterns — autosave, relationships, dangerous predicates, CloudKit constraints, indexing, class inheritance. Use when writing, reviewing, or debugging SwiftData code.
type: guide
origin: https://github.com/twostraws/SwiftData-Agent-Skill
license: MIT
---

> **Guide Skill** — This is an expert workflow/pattern guide, not API reference documentation.
> Originally from [twostraws/SwiftData-Agent-Skill](https://github.com/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

1. Check for core SwiftData issues using `references/core-rules.md`.
2. Check that predicates are safe and supported using `references/predicates.md`.
3. If the project uses CloudKit, check for CloudKit-specific constraints using `references/cloudkit.md`.
4. If the project targets iOS 18+, check for indexing opportunities using `references/indexing.md`.
5. 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` |


---
Source attribution: vabole
Original project: https://github.com/vabole/apple-skills
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Dave AI.

## Upstream license notice

MIT License

Copyright (c) 2026 Ilia Abolhasani

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Dave AI resource metadata

Creator / publisher: vabole
Original project: https://github.com/vabole/apple-skills
Attribution basis: Original project named by vendored-folder README

Fields of work: Development & Engineering, Product Management
Roles: Backend Developer, Mobile Developer, Product Manager
Specialties: Backend, Mobile
Tools: Cloudkit
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 5174266614833edbc63893ec8608ec35c461674af89360afb7a57850aa0a86c7
Metadata reviewed: 2026-10-27
This metadata supersedes earlier Dave AI catalog attribution. Original instruction and supporting files are preserved.