what is sendable type?
Asked on 08/05/2024
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A sendable type in Swift is a type that can be safely transferred between different concurrency domains, such as actors or threads, without causing data races. This is crucial for ensuring data-race safety in concurrent programming.
In Swift, a type is considered sendable if it protects its state from concurrent accesses. For example, a type might qualify as sendable if it acquires a lock while reading and writing mutable state. Swift requires explicit conformance to the Sendable protocol for public types to guarantee to clients that the type is safe to be sent across concurrency boundaries.
Here are some key points about sendable types from the context:
- Public Types: Swift does not infer sendability for public types automatically. You need to explicitly mark them as sendable to avoid locking in sendability prematurely (Migrate your app to Swift 6).
- Data-Race Safety: In Swift 6, the data-race safety of your program is fully verified at compile time. One way to achieve this is by requiring that values shared between concurrency domains are sendable (A Swift Tour: Explore Swift’s features and design).
For more detailed information, you can refer to the session Migrate your app to Swift 6 and A Swift Tour: Explore Swift’s features and design.
A Swift Tour: Explore Swift’s features and design
Learn the essential features and design philosophy of the Swift programming language. We’ll explore how to model data, handle errors, use protocols, write concurrent code, and more while building up a Swift package that has a library, an HTTP server, and a command line client. Whether you’re just beginning your Swift journey or have been with us from the start, this talk will help you get the most out of the language.
What’s new in App Intents
Learn about improvements and all-new features with App Intents, and discover how this framework can help you expose your app’s functionality to Siri, Spotlight, Shortcuts, and more. We’ll show you how to make your entities more meaningful to the platform with the Transferable API, File Representations, new IntentFile APIs, and Spotlight Indexing, opening up powerful functionality in Siri and the Shortcuts app. Empower your intents to take people deep into your app with URL Representable Entities. Explore new techniques to model your entities and intents with new APIs for error handling and union values.
Migrate your app to Swift 6
Experience Swift 6 migration in action as we update an existing sample app. Learn how to migrate incrementally, module by module, and how the compiler helps you identify code that’s at risk of data races. Discover different techniques for ensuring clear isolation boundaries and eliminating concurrent access to shared mutable state.