Core Data to SwiftData Persistence Migration Plan

Role: Staff iOS Persistence Engineer with deep expertise in SQLite, Core Data migration graphs, and SwiftData schemas.

Context

• Existing Core Data Schema Version: {{current_schema_version}}
• Data Volume & Entity Count: {{data_volume_metrics}}
• CloudKit Sync Status: {{cloudkit_integration_mode}}
• Concurrent Access Pattern: {{concurrency_access_profile}}
• Minimum Required iOS Version: {{target_ios_version}}
• Local Persistence Store Type: {{persistent_store_configuration}}

Task

Author a step-by-step technical plan to migrate the persistence architecture of an iOS app from Core Data version {{current_schema_version}} to SwiftData, preserving stored data integrity for {{data_volume_metrics}} under {{concurrency_access_profile}} on {{target_ios_version}}.

Method

1. Analyze entity relationships, transformable attributes, and fetched properties in {{current_schema_version}} to verify compatibility with @Model macros.
2. Design a hybrid or direct initialization strategy for ModelContainer and ModelConfiguration based on {{persistent_store_configuration}}.
3. Define custom migration stages (VersionedSchema, SchemaMigrationPlan) to translate existing Core Data persistent stores without data corruption.
4. Re-architect background context operations and asynchronous batch mutations to utilize ModelActor or detached background contexts.
5. Address CloudKit synchronization constraints according to {{cloudkit_integration_mode}} to prevent schema conflicts.
6. Establish an on-device automated database verification test suite to simulate upgrades from previous release builds.
7. Detail a contingency recovery mechanism for handling corrupted stores or unhandled migration exceptions.

Constraints

• MUST guarantee zero data loss for existing local databases during upgrade.
• MUST NOT execute heavy Core Data or SwiftData fetch operations on the main thread.
• Plan MUST validate compatibility with {{cloudkit_integration_mode}} schema rules.
• Exclude non-Apple third-party persistence frameworks from recommendations.

Output format

Deliver an engineering plan with the following sections:

1. Model & Schema Transformation Blueprint (entity-by-entity mapping)
2. Migration Architecture & Versioned Schema Plan (stepwise execution order)
3. Background Persistence & Thread Isolation Strategy (concurrency patterns)
4. Risk Mitigation & Rollback Protocol (failure triage table) Length should be concise and focused, between 500 and 900 words.

Self-review

• Are all relationship deletion rules and index configurations preserved in the SwiftData models?
• Did I address background persistence safely using ModelActor?
• Does the migration plan handle failure states without crashing the host app?