swift-concurrency-6-2

Swift 6.2 async work stays on the calling actor by default to eliminate implicit background offloading that caused data-race errors. This default behavior enforces single-threaded safety unless explicitly overridden for concurrent tasks.

To offload CPU-bound work to the background in Swift 6.2, explicitly opt-in to concurrent execution using the @concurrent attribute for performance-critical tasks. This ensures heavy computations run safely off the main thread.

MainActor default inference mode in Swift 6.2 reduces boilerplate and eases migration by assuming types run on the MainActor. This enforces single-threaded default behavior for safe concurrency adoption without explicit annotations.

To make MainActor types conform to non-isolated protocols in Swift 6.2, use isolated conformances. This feature allows MainActor-based architectures to safely adopt non-isolated protocols without causing data races.

Migrating to Approachable Concurrency in Swift 6.2 does not require explicit annotations everywhere. Enabling MainActor default inference reduces boilerplate by handling isolation automatically, requiring explicit offloading only for CPU-heavy tasks via @concurrent.

You should explicitly use @concurrent instead of relying on Swift 6.2 default isolation only for performance-critical components requiring CPU-bound work to run in the background. The default isolation handles everything else safely on the calling actor.