What are the biggest changes in Swift this year?

The biggest changes in Swift this year, as presented at WWDC, include:

1. Swift 6 Language Mode: Swift 6 introduces a new language mode that provides data race safety guarantees, which helps in writing correct concurrent programs. This is a significant enhancement for developers working with concurrent code.

2. Non-Copyable Types: Swift 6 introduces non-copyable types. Previously, all Swift types were copyable by default, but now developers can define types that cannot be copied, which can help in optimizing performance and ensuring data integrity.

3. Embedded Swift: A new language subset called Embedded Swift has been introduced, which is designed to run on highly constrained systems such as operating system kernels and microcontrollers. This expands the use cases for Swift into more low-level and resource-constrained environments.

4. Swift Testing Framework: An all-new testing framework named Swift Testing has been introduced. It features expressive APIs that simplify writing tests, making it easier for developers to ensure the quality and reliability of their code.

5. C++ Interoperability: Enhancements have been made to improve interoperability with C++, allowing developers to more easily integrate Swift with existing C++ codebases.

6. Improvements to Concurrency and Generics: There are ongoing improvements to the concurrency model and generics, further refining these core aspects of the language to enhance performance and developer experience.

For more detailed information, you can refer to the session What’s new in Swift starting at 17:03.