Can I use this for complex data transformations?

Absolutely. It includes patterns for Pattern 1b (Heavy Migration) using NSEntityMigrationPolicy for complex changes like splitting fields or changing types.

Why does my migration fail on devices but not the simulator?

The simulator often deletes the database during rebuilds, which masks schema mismatches. This skill provides tools to verify persistent stores on real devices.

How can I fix 'Accessing NSManagedObject on a different thread' errors?

The skill provides patterns for implementing private queue contexts and using async/await properly to maintain thread-confinement.

Does this skill support SwiftData?

Yes, it includes specific diagnostics for scenarios where SwiftData and Core Data are used together or where an app is transitioning between the two.

Core Data Diagnostics & Migration

Name: Core Data Diagnostics & Migration
Author: CharlesWiltgen

byCharlesWiltgen

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233

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Mobile Development

Diagnoses and resolves Core Data crashes, concurrency errors, and schema migration issues using safety-first implementation patterns.

A comprehensive diagnostic framework for Apple's Core Data, designed to identify and fix the most common causes of production crashes and performance bottlenecks in xOS development. This skill provides systematic checklists for debugging schema mismatches, thread-confinement violations, and N+1 query issues, offering battle-tested patterns for both lightweight and complex heavy migrations. It serves as a vital tool for developers needing to maintain data integrity across app updates while managing the transition between traditional Core Data and modern SwiftData architectures.

主な機能

01Thread-confinement and concurrency verification for background processing

02Step-by-step guides for safe lightweight and custom heavy migrations

03SQL profiling patterns to identify and resolve N+1 query performance leaks

04Architectural bridging patterns for mixing SwiftData and Core Data on the same store

05Systematic schema mismatch detection and 'Unresolvable fault' diagnostics

06233 GitHub stars

ユースケース

01Optimizing app responsiveness by identifying inefficient relationship fetching

02Safely transforming complex data types during major database version updates

03Debugging production launch crashes following a schema change

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add charleswiltgen/axiom axiom-core-data-diag

For use in Claude.ai and ChatGPT

Download Skill