core_data_cloudkit.md

CloudKit and Core Data

• Core Data and CloudKit are conceptually similar but implemented in very different ways.
• You can now check a use CloudKit checkbox when you add Core Data to your app.
• You need to add the iCloud and Background mode capabilities yourself in order to use CloudKit and update your app in the background.
• Xcode creates a container identifier for your app.
• NSPersistentCloudKitContainer managed persistent stores that sync data too iCloud. The CloudKit container is a subclass of the NSPersistentContainer.
• The CloudKit container contains all the boilerplate code that you would normally have to write yourself.
• Apple asks for feedback on this container explicitly.
• CloudKit container creates a local replica of the CloudKit store.
• You can add separate stores for cloud and non-cloud synced entities. You can use persistent store descriptions to tell the container which stores it manages.
• A persistent CloudKit container can share data across multiple applications by creating a shared sqlite file.
• The container understands how to optimize certain CloudKit storage aspects, for instance, it's able to use either an asset or plain string to store text of variable length.
• One to many relationships do not use ckreference because there is a limit of 750 references for an item. Instead they use UUIDs so they have unlimited references.
• Many to many relationships are implemented through a linking table.
• When modeling for collaboration and you have a textfield, you might want to use a to many relationship for the textfield content so conflicts can't happen (as easily).

Worth watching, documentation is updated.