Swift currently has no language-level concurrency model at all (the only concurrency support available is through libraries such as pthread and libdispatch). However, real concurrency support is on the roadmap for Swift 6 [0] (probably based on some combination of async/await and an actor model), and the core team is expected to release an initial design document within the next few weeks.

[0]: https://forums.swift.org/t/on-the-road-to-swift-6/32862/