ios-data-persistence

Choosing between SwiftData and Core Data for iOS data persistence depends on your app's architecture and sync needs. SwiftData offers a modern Swift-native API, while Core Data provides mature, granular control. The Skill provides decision trees to select the correct structured database framework and avoid mixing them, which causes data loss.

To implement safe schema migrations for an iOS app database, you must use additive and idempotent migration steps. The Skill provides implementation guides and anti-pattern warnings to ensure your SwiftData or Core Data schema updates do not cause data loss or migration crashes for your existing user base.

CloudKit sync fails and causes data loss in SwiftData apps often due to schema deployment gaps, offline-first workflow conflicts, or unsafe migrations. The Skill provides step-by-step diagnostic steps and anti-pattern warnings to resolve sync failures and ensure conflict-resilient iCloud workflows.

Yes, you can use iCloud Drive for user-exported file storage and Keychain for auth tokens in a cross-device iOS app. The Skill provides end-to-end decision guidance to map data to the correct storage location, ensuring structured records use SwiftData while files and secrets are stored separately.

You need GRDB or SQLiteData instead of Core Data for local persistence when you require direct SQLite access or specific database features not exposed by higher-level frameworks. The Skill provides multi-framework implementation guides and decision trees to help you select the correct storage format for your specific data type.

The limitations of using UserDefaults for data persistence on iOS include backup bloat and potential data loss when storing complex structured records instead of user preferences. The Skill provides anti-pattern warnings and configuration guidance to ensure UserDefaults is used appropriately and data is stored in the correct format.