Which versions of iOS does this target?

This skill is optimized for iOS 17 and above, with specific considerations for features and bugs found in the early SwiftData releases.

How does this skill handle property type changes?

It implements a two-stage migration pattern using an intermediate schema that contains both old and new property types to safely transform data.

What is the main limitation of SwiftData migrations?

SwiftData's willMigrate closure only sees the old schema, while didMigrate only sees the new one, preventing direct data transfer between versions in a single step.

Does this support many-to-many relationships?

Yes, it provides specific guidance on explicit inverse relationships and array requirements needed to preserve many-to-many links during migration.

SwiftData Migration Expert

Name: SwiftData Migration Expert
Author: CharlesWiltgen

byCharlesWiltgen

•

233

•

Mobile Development

Implements complex SwiftData schema migrations using two-stage patterns to overcome model versioning limitations.

This skill provides a specialized framework for managing SwiftData migrations that exceed the capabilities of automatic lightweight updates. It addresses the critical architectural constraint where SwiftData's migration closures cannot access old and new models simultaneously. By utilizing VersionedSchema and SchemaMigrationPlan patterns, the skill enables developers to safely perform property type changes, preserve complex relationships, and execute data transformations while ensuring data integrity across iOS, iPadOS, and watchOS apps.

주요 기능

01Two-stage migration patterns for property type transformations

02233 GitHub stars

03Complete VersionedSchema snapshot implementation guidance

04Workarounds for iOS 17+ SwiftData relationship bugs

05Preservation of one-to-many and many-to-many relationships

06Prefetching strategies to maintain data links during migration

사용 사례

01Changing a property from String to AttributedString without data loss

02Migrating many-to-many relationships with explicit inverse requirements

03Converting optional properties to required properties with default population

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add charleswiltgen/axiom axiom-swiftdata-migration

For use in Claude.ai and ChatGPT

Download Skill