ManagedModels for CoreData

Instead of wrapping CoreData, directly use it :-)

The key thing ManagedModels provides is a @Model macro, that works similar (but not identical) to the SwiftData @Model macro. It generates an NSManagedObjectModel straight from the code. I.e. no CoreData modeler / data model file is necessary.

Example:

****TODO****

This is not a replacement implementation of SwiftData. I.e. the API is kept similar to SwiftData, but not exactly the same. It doesn't try to hide CoreData, but rather provides utilities to work with CoreData in a similar way.

Requirements

The macro implementation requires Xcode 15/Swift 5.9 for compilation. The generated code itself though should backport way back to iOS 10 / macOS 10.12 though (when NSPersistentContainer was introduced).

Differences to SwiftData

• The model class must explicitly inherit from NSManagedObject (superclasses can't be added by macros), e.g. @Model class Person: NSManagedObject.
• ToMany relationships must be a Set<Target>, a plain [ Target ] cannot be used (yet?). E.g. var contacts : Set<Contact>.
• Properties cannot be initialized in the declaration, e.g. this doesn't work: var uuid = UUID(). Must be done in an initializers (requirement by @NSManaged).
• Doesn't use the new Observation framework (which requires iOS 17+), but uses ObservableObject (which is directly supported by CoreData).

TODO

• Archiving/Unarchiving, required for migration.
• Figure out whether we can do ordered attributes.
• Figure out whether we can add support for array toMany properties.
• Support for "autosave".
• Support transformable types, not sure they work right yet.
• Generate property initializers if the user didn't specify any inits?
• Generate fetchRequest() class function.
• Support SchemaMigrationPlan/MigrationStage.
• Write more tests.
• Write DocC docs.
• Support for entity inheritance.
• Add support for originalName/versionHash in @Model.
• Generate "To Many" accessor function prototypes (addItemToGroup etc).
• Foundation Predicate support (would require iOS 17+)
  • SwiftUI @Query property wrapper/macro?
• Figure out all the cloud sync options SwiftData has and whether CoreData can do them.
• Figure out whether we can allow initialized properties (var title = "No Title").

Pull requests are very welcome! Even just DocC documentation or more tests would be welcome contributions.

Links

• Apple:
  • CoreData
  • SwiftData
• Lighter.swift, typesafe and superfast SQLite Swift tooling.

Disclaimer

SwiftData and SwiftUI are trademarks owned by Apple Inc. Software maintained as a part of the this project is not affiliated with Apple Inc.

Who

Models are brought to you by Helge Heß / ZeeZide. We like feedback, GitHub stars, cool contract work, presumably any form of praise you can think of.