Swift 6.4 is now available, deepening support for applications, servers, systems code, embedded devices and web browsers. The release streamlines programming with clearer, simpler code.
A core update establishes Swift Build as the default build system within Swift Package Manager, replacing previous systems to ensure consistent compilation across Linux, macOS, and Windows environments. This standardization provides a unified build experience across integrated development environments and continuous integration platforms, enabling Swift packages to build and run full test suites on macOS, iOS, Linux and Windows.
Swift's reach expands with deeper language interoperability, including enhanced capabilities with systems-level C++, Android's Java runtime, WebAssembly for browser applications and Embedded Swift for microcontrollers.
For WebAssembly, JavaScriptKit now offers significantly faster performance when bridging to Wasm. Safe bridging operations are up to 40 times faster than earlier dynamic bridging methods. The Wasm SDK is available directly from the Swift.org install page, removing the need for additional setup to compile Swift for browsers.
Swift on Android continues to advance with the Swift SDK built on the new Long Term Support NDK 30, which provides Android availability attributes in Swift runtime libraries and packages. Swift Build also supports Android within Swift Package Manager.
The Subprocess library has reached its 1.0 milestone, providing a cross-platform package for running and interacting with subprocesses using Swift concurrency.
Developers can combine asynchronous calls within defer blocks and cancellation shields, ensuring cleanup work executes regardless of how a function returns. Improvements to Foundation and the standard library facilitate using modern APIs with existing types—ProgressManager now supports async/await, and types feature fine-grained change notifications.
Migrating existing projects to Swift Testing is now easier. Developers can use XCTAssert within Swift Testing tests or #expect within XCTests, while the CustomTestReflectable protocol allows customization of values displayed in failed expectations. The swift test command supports repeating test cases and recording attachments on Apple platforms.
Swift 6.4 includes tooling improvements for debugging, building and editor support. A new Swift documentation site is available, with standard library documentation now open source. Debug builds on Linux and Windows, along with dSYM bundles on macOS, show significant size reductions because binary Swift modules are no longer embedded in these debug artifacts.
