Core Data

For apps still on Core Data rather than SwiftData, this covers the full persistence stack: setting up NSPersistentContainer, threading rules with perform blocks, NSFetchedResultsController for table views, and batch operations that run at SQL level. It includes iOS 17+ features like staged migrations and composite attributes, plus persistent history tracking for multi-target sync. The concurrency section is solid on the "never pass NSManagedObject across threads" rule and shows how to use objectID with Swift concurrency. If you're maintaining a Core Data codebase or need features SwiftData doesn't expose yet, this has the patterns you actually use in production, not just CRUD basics.

skills.sh installs: 2.8K
GitHub stars: 1.3K
last updated: Aug 21, 2026

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Install

$ npx -y skills add dpearson2699/swift-ios-skills --skill core-data --agent claude-code

Installs into .claude/skills of the current project.

Files

Core Data

Build and maintain data persistence using Core Data for apps that have not adopted SwiftData. Covers stack setup, concurrency, batch operations, NSFetchedResultsController, persistent history tracking, staged migration, and testing.

Stack Setup
Concurrency and Threading
NSFetchedResultsController
Batch Operations
Persistent History Tracking
Staged Migration
Composite Attributes
SwiftData Boundary
Testing
Common Mistakes
Review Checklist
References

Stack Setup

NSPersistentContainer encapsulates the Core Data stack.

Docs: NSPersistentContainer

import CoreData

final class CoreDataStack: @unchecked Sendable {
    static let shared = CoreDataStack()

    let container: NSPersistentContainer

SKILL.md on GitHub

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Details

Repository: github.com/dpearson2699/swift-ios-skills
Categories: DevOps & CI/CD, Git & Pull Requests, Code Review & Quality, Mobile Development
First seen: Jun 3, 2026

Core Data

Install

Files

Core Data

Contents

Stack Setup

Details

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