swift-concurrency-6-2

Single-threaded defaults in Swift 6.2 concurrency keep code executing on the caller's actor by default, reducing data races caused by implicit offloading. You explicitly opt into background execution only when needed for specific tasks.

To migrate a Swift project to 6.2 concurrency safely, apply single-threaded defaults, use isolated conformances to prevent unsafe access, and adopt the @concurrent attribute specifically for CPU-bound background work.

Use the @concurrent attribute in Swift when you need to explicitly offload CPU-bound tasks to background execution. It allows you to opt into concurrency intentionally rather than relying on implicit offloading.

MainActor isolation prevents data races in UI apps by ensuring code executes on the main thread by default. This single-threaded default model means concurrent access only happens through explicit opt-in, keeping state predictable.

Isolated conformances in Swift are a concurrency pattern that restricts protocol access to specific actors. You need them during migration to safely adopt Swift 6.2 patterns and avoid unsafe cross-actor data access.

Swift 6.2 concurrency minimizes data races from implicit task offloading by adopting a model where code remains on the caller's actor by default. This approach requires explicit opt-in for background execution, making code behavior predictable.