swift-6-migration

Migrate to Swift 6 by enabling Swift 6 language mode for your targets, then enable complete concurrency checking to identify data race and Sendable conformance issues. Apply fixes incrementally following the migration guide, adopting async/await and actors to resolve warnings before full deployment.

Sendable conformance ensures types are safe to share across actor boundaries and concurrent contexts. Swift 6's complete concurrency checking enforces Sendable to prevent data races; you must mark types Sendable or redesign them to isolate mutable state within actors.

Yes, Swift 6 supports incremental migration through complete checking mode, which emits warnings before errors. Enable it per-target, fix issues in stages across libraries and tests, and gradually adopt async/await and actor isolation without requiring all changes simultaneously.

Swift 6 language mode enables the language's concurrency features; complete concurrency checking enforces strict data race safety rules. Enable language mode first on your targets, then activate complete checking to surface Sendable and actor isolation violations as warnings, then errors.

Async/await is not strictly required, but Swift 6 migration focuses on concurrency safety and actor isolation. You must fix data race warnings and Sendable conformance issues; async/await and actors are the idiomatic solutions that eliminate most concurrency violations in Swift 6.

Run complete concurrency checking on your test targets and apply the same migration steps: fix Sendable violations, isolate mutable state in actors, and adopt async/await where needed. The migration guide provides incremental testing strategies to verify changes safely across your test suite.