swift-data-persistence

name	swift-data-persistence
description	Data persistence patterns for Swift apps using SwiftData, CoreData, UserDefaults, and Keychain.
activation	Load when implementing data storage or persistence in Swift

Skill: swift-data-persistence

Overview

Data persistence patterns for Swift apps.

SwiftData (iOS 17+, Default)

• Use @Model for entities.
• Use @Attribute and @Relationship for schema details.
• Use ModelContext for CRUD operations.
• Use @Query in SwiftUI Views for live data binding.
• Handle migrations: lightweight (automatic) vs manual (custom migration code).
• CloudKit sync is optional; mention when cloudKitContainer is configured.

CoreData (Legacy)

• Mentioned for compatibility only.
• Prefer SwiftData for new code.
• Basic patterns: NSManagedObject, NSFetchRequest, NSPersistentContainer.

UserDefaults

• Use only for simple settings (booleans, small strings).
• Never store sensitive data in UserDefaults.

Keychain

• Use for sensitive data (tokens, passwords, credentials).
• Describe the pattern; do not mandate a specific third-party library.