Swift 6.3 introduces the first official Android SDK and improved C interoperability

Swift 6.3 has been released, bringing the first official Swift SDK for Android. This allows developers to build native Android apps in Swift, adapt Swift packages for Android, and integrate Swift code into Kotlin or Java projects. The release also expands Swift’s reach in embedded environments and large scale systems with broader platform support and build improvements.

One of the main language additions is the new @c attribute, which lets Swift functions and enums be exposed to C code within the same project. Developers can assign custom C symbol names and, when combined with @implementation, connect Swift functions to existing C declarations for better interoperability in mixed language codebases. Swift 6.3 also introduces module selectors, making it easier to resolve naming conflicts when multiple imported modules expose APIs with the same name.

On the tooling side, Swift 6.3 includes a preview of Swift Build integration in Swift Package Manager for a more consistent cross platform build experience. It also adds new optimization controls such as @specialize and @inline(always), along with improvements to macro library support, package documentation, and testing. DocC now supports Markdown output and new accessibility focused enhancements for documentation.