what’s new in concurrency

Asked on 2025-07-03

@wwdc25

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In the WWDC 2025 sessions, several updates and improvements related to concurrency in Swift were introduced:

  1. Swift 6.2 Concurrency Enhancements: Swift 6.2 introduces changes to make concurrency more approachable. By default, code runs on the main actor, reducing the risk of data races. When you start using async functions, they run wherever they're called from, maintaining data safety. You can offload specific code to the background to run in parallel when ready to embrace concurrency for performance improvements. These changes are opt-in and can be enabled in Xcode Build Settings or a Swift package manifest file. What’s new in Swift

  2. Xcode 26 Debugging Improvements: Xcode 26 has improved its debugging capabilities for Swift concurrency. It now follows execution into asynchronous functions and displays task IDs in the debugger UI, making it easier to debug concurrency issues. What’s new in Xcode

  3. Concurrency in SwiftUI: SwiftUI leverages concurrency to improve app performance and responsiveness. Swift 6.2 introduces a new language mode that marks all types in a module with the mainactor annotation implicitly, helping to avoid data race bugs. Explore concurrency in SwiftUI

  4. Approachable Concurrency Configuration: New app projects in Xcode 26 have features enabled by default that provide a more approachable path to introducing concurrency, such as the Main Actor by default mode. Code-along: Elevate an app with Swift concurrency

These updates aim to make concurrent programming in Swift safer and more accessible, allowing developers to write efficient and responsive applications.