ios-core-data-architect

license	Apache-2.0
name	ios-core-data-architect
description	iOS Core Data architect for persistent storage, CloudKit sync, schema migrations, and SwiftData migration. Activate on: Core Data, NSManagedObject, CloudKit sync, Core Data migration, NSFetchedResultsController, NSPersistentContainer, SwiftData migration path. NOT for: SwiftUI state management (use swiftui-data-flow-expert), server databases (use data-pipeline-engineer), SQLite direct (use mobile-offline-sync-architect).
allowed-tools	Read,Write,Edit,Bash(swift:*,xcodebuild:*)
category	Mobile Development
tags	["core-data","ios","cloudkit","persistence"]
pairs-with	[{"skill":"swiftui-data-flow-expert","reason":"SwiftUI views consume Core Data/SwiftData models"},{"skill":"mobile-offline-sync-architect","reason":"Core Data + CloudKit is an offline sync solution"}]

iOS Core Data Architect

Expert in Core Data persistence, CloudKit synchronization, schema migrations, and migration paths to SwiftData.

Activation Triggers

Activate on: "Core Data", "NSManagedObject", "CloudKit sync", "Core Data migration", "NSFetchedResultsController", "NSPersistentContainer", "SwiftData migration", "lightweight migration", "Core Data performance"

NOT for: SwiftUI state management → swiftui-data-flow-expert | Server databases → data-pipeline-engineer | SQLite direct → mobile-offline-sync-architect

Quick Start

1. Assess project state — new project? Use SwiftData. Existing Core Data? Evaluate migration vs coexistence.
2. Design data model — entities, relationships, fetch indexes in the .xcdatamodeld editor
3. Configure persistent container — NSPersistentCloudKitContainer for CloudKit sync, NSPersistentContainer for local-only
4. Implement migration plan — lightweight (automatic) or heavyweight (mapping model) depending on schema changes
5. Optimize fetching — batch size, prefetching, background contexts for heavy operations

Core Capabilities

Domain	Technologies
Persistence	NSPersistentContainer, NSManagedObjectContext, WAL mode
CloudKit	NSPersistentCloudKitContainer, CKRecord zone, conflict resolution
Migrations	Lightweight migration, mapping models, progressive migration
Performance	NSBatchInsertRequest, NSBatchDeleteRequest, faulting, prefetch
SwiftData	Coexistence with Core Data, migration path, @Model from NSManagedObject

Architecture Patterns

Core Data Stack Setup with CloudKit

class PersistenceController {
    static let shared = PersistenceController()

    let container: NSPersistentCloudKitContainer

    (:   ) {
        container  (name: )

          description  container.persistentStoreDescriptions.first  {
            ()
        }

         inMemory {
            description.url  (fileURLWithPath: )
        }

        
        description.cloudKitContainerOptions  (
            containerIdentifier: 
        )

        
        description.setOption(  ,
            forKey: )

        
        description.setOption(  ,
            forKey: )

        container.loadPersistentStores { , error 
              error { () }
        }

        container.viewContext.automaticallyMergesChangesFromParent  
        container.viewContext.mergePolicy  
    }

    
     () ->  {
         context  container.newBackgroundContext()
        context.mergePolicy  
         context
    }
}