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. Contents - 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 encapsulates the Core Data stack. Docs: NSPersistentContainer For CloudKit sync, use instead…