wwcd21 Protect mutable state with Swift actors
Asked on 2026-04-13
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To protect mutable state with Swift actors, you can utilize the actor model in Swift, which is designed to handle concurrency safely by serializing access to its state. Actors in Swift are similar to classes but automatically protect their state by ensuring that only one task can execute at a time on an actor. This prevents data races and ensures that mutable state is accessed safely.
In the session A Swift Tour: Explore Swift’s features and design, it is explained that actors encapsulate shared mutable state and serialize accesses to it, making concurrent accesses safe. This is particularly useful when you have mutable state that needs to be accessed from different concurrency domains.
Additionally, in the session What’s new in Swift, it is mentioned that the main actor can be used to protect global state by annotating an entire class with the main actor, which is especially useful in projects that do not have a lot of concurrent tasks. This approach reduces concurrency annotations in code that is mostly single-threaded.
If you are interested in learning more about preventing data races with Swift 6, you can refer to the session Code-along: Elevate an app with Swift concurrency, which discusses strategies for preventing data races using Swift's concurrency features.
Code-along: Elevate an app with Swift concurrency
Learn how to optimize your app’s user experience with Swift concurrency as we update an existing sample app. We’ll start with a main-actor app, then gradually introduce asynchronous code as we need to. We’ll use tasks to optimize code running on the main actor, and discover how to parallelize code by offloading work to the background. We’ll explore what data-race safety provides, and work through interpreting and fixing data-race safety errors. Finally, we’ll show how you can make the most out of structured concurrency in the context of an app.
What’s new in Swift
Join us for an update on Swift. We’ll talk about workflow improvements that make you more productive, and new and modernized library APIs for fundamental programming tasks. We’ll show examples of Swift adoption throughout more layers of the software stack. Finally, we’ll explore new language features for both improving approachability of concurrency, and achieving peak performance when you need it.
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.