@delawaremathguy Thanks for the original set of posts/replies on this subject. After re-reading them multiple times I was able to find the way to get nil into an Id of type UUID for another Entity. I have an Entity named "Hour" that will eventually be associated with an "Invoice" Entity but I haven't yet created the "Invoice" so I don't have access to it's Id whichs is an UUID.

Solution: I have an "Hour" attribute named invoiceId that is a UUID? NOTE: the Optional ?. Then using SwiftData's init it creates invoiceId: UUID? = nil So when I create the Hour entity without an Invoice the initializer for the invoiceId is this: invoiceId: nil

Hope this will assit others.

hi Michael,

as i did last time, i'll start my reply: "took a few minutes to remember this ..." it looks like you are referencing this thread.

i'm happy you are good with the idea.

i have two quick comments to add at the moment, as i, too, am exploring SwiftData right now:

• i don't see that you can have your own implementation of an id property in your SwiftData models. if you have such an attribute now (Core Data seems OK with this), and you want to have SwiftData use the data store you already have, you would first need to migrate your current Core Data entity, renaming the existing id attribute to something else, e.g., a referenceID.

• however, if Core Data is working with NSPersistentCloudKitContainer, you have a problem: renaming does not work with CloudKit.

thanks for the mention, and as i said, you can find me on GitHub.

DMG

In SwiftData, when creating entities that possess attributes referring to UUIDs of other entities, it's crucial to ensure seamless initialization and management UUIDs, or Universally Unique Identifiers, play a pivotal role in uniquely identifying these entities across the system.