What's the biggest change in Swift 6?

Generated on 8/5/2024

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The biggest change in Swift 6 is the introduction of the new Swift 6 language mode, which provides data race safety guarantees. This new mode helps ensure that concurrent programs are correct by diagnosing concurrent access to memory at compile time. This feature is opt-in, allowing developers to adopt it incrementally, module by module, and even interoperate with dependencies that may not have migrated to the Swift 6 language mode yet.

Additionally, Swift 6 introduces several other improvements, including:

  • Non-copyable types: These types suppress the default copyability of Swift types, making them suitable for scenarios requiring unique ownership, such as managing system resources like files.
  • Embedded Swift: A new language subset designed to run on highly constrained systems, such as operating system kernels and microcontrollers.
  • Concurrency improvements: Enhancements to the concurrency model, including better data race checking and the ability to pass non-sendable values across active isolation boundaries safely.
  • Swift Testing: A new testing framework built from the ground up for Swift, offering expressive APIs to simplify writing tests.

For more details, you can refer to the session What’s new in Swift (02:57).