@wwdc21 Protect mutable state with Swift actors

To protect mutable state with Swift actors, you can utilize the actor model introduced in Swift. Actors are reference types similar to classes, but they automatically protect their state by serializing accesses, ensuring that only a single task can execute at a time on an actor. This helps prevent data races, which can occur when multiple threads try to access and mutate shared data simultaneously.

In the session titled "A Swift Tour: Explore Swift’s features and design" from WWDC 2024, it is explained that actors encapsulate shared mutable state and provide a convenient way to ensure data race safety. Calls to actor methods from outside the actor's context are asynchronous, requiring the use of the await keyword. This ensures that concurrent accesses are synchronized, eliminating data race conditions (A Swift Tour: Explore Swift’s features and design).

Additionally, the session "What’s new in Swift" from WWDC 2025 discusses the use of the main actor to protect mutable state by default. This is particularly useful in projects that are mostly single-threaded, as it reduces the need for concurrency annotations and helps prevent data race safety errors (What’s new in Swift).

For more practical guidance, the session "Code-along: Elevate an app with Swift concurrency" provides examples of how to prevent data races by isolating mutable state to the main actor and using sendable value types (Code-along: Elevate an app with Swift concurrency).