Swift 6.4

Swift 6.4 has been released — Apple announced the latest version of its flagship programming language at WWDC26, bringing a wave of ergonomic improvements, cross-platform expansions, and concurrency refinements. Here is the full breakdown.

What Changed

Swift 6.4, unveiled alongside Swift 6.3 as a combined WWDC26 release, focuses on reducing boilerplate and extending Swift reach beyond Apple platforms. The release includes several long-awaited language features and the first official Swift SDK for Android.

Everyday Language Improvements

Several quality-of-life changes landed in Swift 6.4. The new anyAppleOS availability shorthand replaces verbose platform lists — instead of listing iOS, macOS, watchOS, tvOS, and visionOS individually, developers can now use a single macro. The @diagnose attribute gives finer-grained control over compiler deprecation warnings, letting teams suppress or elevate specific diagnostics without blanket flags.

Module selectors, using the :: syntax, resolve name collisions between imported modules. The @C attribute now allows Swift functions to be directly exposed to C code, a significant step for mixed-language codebases and gradual migration from C to Swift.

Concurrency and Ownership

The Iterable protocol extends for-in loop support to custom types, making iteration more flexible. Borrow and mutate accessors give developers fine-grained control over value semantics. The @inline(always) attribute provides explicit inlining hints for performance-critical code paths.

Optional any and some keywords no longer require parentheses, cleaning up existential type syntax. Task cancellation now works inside defer blocks as expected, closing a longstanding gap in the concurrency model.

Cross-Platform Push

Swift 6.4 ships the first official Swift SDK for Android, available directly from swift.org. Combined with the new Swift extension for VS Code that integrates with Swiftly toolchain management, the Android SDK marks a major milestone in Swift journey beyond Apple ecosystems.

Swift Package Manager 6.4 makes Swift Build the new default build system, unifying the build experience across all supported platforms — macOS, Linux, Windows, and now Android.

Why It Matters

Swift 6.4 represents the most significant language evolution since Swift 5.7. Between the Android SDK, C interoperability via @C, and concurrency refinements, this release positions Swift as a genuinely multi-platform language — not just an Apple tool.

Swift 6.4 is available now via Xcode 27 and from swift.org. Upgrade through Swiftly or your package manager of choice.