Swift 6.2 Approachable Concurrency

Patterns for adopting Swift 6.2's concurrency model where code runs single-threaded by default and concurrency is introduced explicitly.

When to Activate

• Migrating Swift 5.x or 6.0/6.1 projects to Swift 6.2
• Resolving data-race safety compiler errors
• Designing MainActor-based app architecture
• Offloading CPU-intensive work to background threads
• Enabling Approachable Concurrency build settings in Xcode 26

Core Problem

In Swift 6.1 and earlier, async functions could be implicitly offloaded to background threads, causing data-race errors. Swift 6.2 fixes this: async functions stay on the calling actor by default.

Core Pattern -- Isolated Conformances

MainActor types can now conform to non-isolated protocols safely: