Swift 6.4 introduces Swift Build as the default build system for the Swift Package Manager, ensuring consistent project compilation across Linux, macOS, and Windows. The release also marks the 1.0 milestone for the Subprocess library, which provides a cross-platform interface for executing and interacting with external programs.
The update enhances language interoperability across the stack. Swift now supports direct mapping between its Span type and C++20 std::span. Additionally, Swift/Java interoperability has been expanded to include better support for async and callback functions, while the WebAssembly bridge via JavaScriptKit has seen performance improvements of up to 40 times.
Embedded Swift development receives significant updates, including support for existential types and improved error handling for microcontrollers. The release also introduces new memory management features, such as non-copyable array types and the Iterable protocol, which allow developers to optimize performance by avoiding unnecessary data copying while maintaining memory safety.
Tooling improvements include the integration of Software Bill of Materials (SBOM) generation in SPDX or CycloneDX formats within SwiftPM. The Swift extension for VS Code is now available in the Open VSX registry, supporting various IDEs like Cursor and Kiro. Furthermore, debugging is more efficient as the compiler now uses precise dependency tracking for modules.
