swiftdata · dpearson2699 — Claude Code skill: SwiftData models, queries

What swiftdata does

The skill loads a guide the agent reads before touching your data layer. It covers @Model classes, @Attribute options such as .externalStorage and .unique, delete rules on @Relationship, and compound keys declared with #Unique. Separate sections handle @Query in SwiftUI, #Predicate, FetchDescriptor, plus schema versioning with VersionedSchema and SchemaMigrationPlan.

CloudKit gets its own treatment. Before advising on sync, the agent checks that the target has the iCloud capability with CloudKit and the right container, and that Background Modes includes remote notifications. It also flags schema traits that break sync. Model objects stay tied to their context and actor, so the guide has you pass a PersistentIdentifier across actors instead of the instance.

The requirements are iOS 26+ and Swift 6.3. Model inheritance and the newer syntax will not build on older toolchains. For background work there is a @ModelActor section. Batch deletes deserve care: the skill tells you to run the exact predicate against a throwaway copy of the store first, then refetch and check counts, because a wrong #Predicate removes rows you meant to keep.