Swift Concurrency

Overview

Structured concurrency built on async/await. The compiler enforces isolation (actor, @MainActor) and, under Swift 6 strict concurrency, data-race safety via Sendable. Prefer this over GCD/DispatchQueue for new code.

When to use

• Async iOS work: network, disk, or shared-KMP calls
• Updating UI safely from background work (@MainActor)
• Parallel work (async let, TaskGroup)
• Bridging callback/delegate APIs into async (withCheckedContinuation)
• Compiler errors like "call to main actor-isolated … in a synchronous nonisolated context" or Sendable warnings
• Consuming Kotlin suspend/Flow surfaced as Swift async (see kmp-ios-integration)

Quick reference