Does swift data supports deduplication with iCloud sync?

Generated on 3/29/2025

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Yes, Swift Data supports deduplication with iCloud sync through the use of a new schema macro that allows you to construct a compound constraint on persistent models. You can use the unique macro to specify which combinations of your model's properties must remain unique. When two model instances share the same unique values, Swift Data will perform an upsert on collision with an existing model, effectively avoiding duplicates. This feature is part of the enhancements introduced in Swift Data, as discussed in the session What’s new in SwiftData.

Track model changes with SwiftData history

Track model changes with SwiftData history

Reveal the history of your model’s changes with SwiftData! Use the history API to understand when data store changes occurred, and learn how to use this information to build features like remote server sync and out-of-process change handing in your app. We’ll also cover how you can build support for the history API into a custom data store.

Platforms State of the Union

Platforms State of the Union

Discover the newest advancements on Apple platforms.

What’s new in SwiftData

What’s new in SwiftData

SwiftData makes it easy to add persistence to your app with its expressive, declarative API. Learn about refinements to SwiftData, including compound uniqueness constraints, faster queries with #Index, queries in Xcode previews, and rich predicate expressions. Join us to explore how you can use all of these features to express richer models and improve performance in your app. To discover how to build a custom data store or use the history API in SwiftData, watch “Create a custom data store with SwiftData” and “Track model changes with SwiftData history”.

What’s new in Swift

What’s new in Swift

Join us for an update on Swift. We’ll briefly go through a history of Swift over the past decade, and show you how the community has grown through workgroups, expanded the package ecosystem, and increased platform support. We’ll introduce you to a new language mode that achieves data-race safety by default, and a language subset that lets you run Swift on highly constrained systems. We’ll also explore some language updates including noncopyable types, typed throws, and improved C++ interoperability.

Create a custom data store with SwiftData

Create a custom data store with SwiftData

Combine the power of SwiftData’s expressive, declarative modeling API with your own persistence backend. Learn how to build a custom data store and explore how to progressively add persistence features in your app. To get the most out of this session, watch “Meet SwiftData” and “Model your schema with SwiftData” from WWDC23.