swift-concurrency-6-2

Topics in the source

• Swift 6.2 Approachable Concurrency
• When to Activate
• Core Problem: Implicit Background Offloading
• Core Pattern — Isolated Conformances
• Core Pattern — Global and Static Variables
• MainActor Default Inference Mode
• Core Pattern — @concurrent for Background Work
• Key Design Decisions

Patterns for adopting Swift 6.2's concurrency model where code runs single-threaded by default and concurrency is introduced explicitly. Eliminates common data-race errors without sacrificing performance. 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 Implementing protocol conformances on MainActor-isolated types Enabling Approachable Concurrency build settings in Xcode 26 In Swift 6.1 and earlier, async functions could be implicitly offloaded to background threads, causing data-race errors even in seemingly safe code: Swift 6.2 fixes this: async functions stay on the calling actor by default. MainActor types can now conform to non-isolated protocols safely: The compiler ensures the conformance is only used on the main actor: Protect global/static state with MainActor: Swift 6.2 introduces a mode where MainActor is inferred by default — no manual annotations needed: This mode is opt-in and recommended for apps, scripts, and other executable targets. When you need actual parallelism, explicitly offload with @concurrent: Important: This examp

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