Swift 6 is now available! This major release takes Swift to new heights, expanding its reach across more platforms and domains.

While Swift is widely known for app development—powering over a million apps on the App Store—its safety, speed, and versatility make it ideal for many other use cases. Whether you’re building libraries, large-scale services, or performance-critical code, Swift is a powerful tool.

Swift 6 pushes these boundaries further with new low-level programming features, enhanced platform support, and the introduction of Embedded Swift. Additionally, there’s a new Swift Testing library, cross-platform APIs, and much more.

Let’s dive into some of the exciting new features in Swift 6:

🔗 Language and Standard Library Enhancements 🔗

Concurrency

Swift 6 introduces a new, opt-in language mode that extends Swift’s legendary memory safety to prevent data races in concurrent code. Previously, data-race safety checks were available as warnings in Swift 5.10, but now they’ve been elevated to compiler errors in Swift 6. Improved Sendable inference and new compiler analysis further reduce false positives, making concurrency safer and easier to manage.

Alongside this, Swift 6 includes a new Synchronization library for low-level concurrency, featuring atomic operations and a new mutex API to support robust multi-threaded applications.

Typed Throws

In Swift 6, you can now specify the type of error a function throws as part of its signature. This feature is essential for generic code or in environments like Embedded Swift, where memory allocation may be constrained. This allows more precise error handling and reduces ambiguity in codebases.

Ownership

Building on non-copyable types introduced in Swift 5.9, Swift 6 fully integrates this feature into the generics system. Developers can now work seamlessly with both copyable and non-copyable types, further optimizing performance and resource management in Swift applications.

C++ Interoperability

Swift 6 expands on Swift’s bidirectional interoperability with C++, supporting move-only types, virtual methods, and more. This means developers can integrate Swift into existing C++ codebases even more efficiently.

🛠️ Embedded Swift: A Preview for Low-Level Development 🛠️

One of the most exciting features in Swift 6 is the preview of Embedded Swift. This is a subset of the Swift language designed for low-level, memory-constrained environments like microcontrollers. Embedded Swift produces lightweight, standalone binaries, making it perfect for embedded systems and bare-metal development.

📚 Productivity Enhancements in Swift 6 📚

To help developers write cleaner, more efficient code, Swift 6 introduces several productivity enhancements, including:

• count(where:): Easily count elements in a sequence that match a condition.
• Pack iteration: Write more natural for loops over elements in value parameter packs.
• Access control for imports: Prevent internal implementation details from leaking into public APIs.

🛠️ Swift Testing: A New Testing Library 🛠️

Swift 6 brings a powerful new Swift Testing library to simplify testing in Swift. The library leverages expressive APIs and macros to write, organize, and scale tests easily, all while providing detailed feedback when things go wrong.

For example, Swift Testing uses macros like @Test to define tests and #expect to validate behaviors, making testing more intuitive and powerful. Swift Testing is cross-platform and available for macOS, Linux, and Windows, ensuring that your tests run consistently across all environments.

🌍 Cross-Platform Support and Improvements 🌍

Swift 6 continues to expand its cross-platform capabilities, especially for Linux and Windows. It brings support for more Linux distributions, including Debian, Fedora, and Ubuntu 24.04, as well as improved build performance for Windows on ARM architectures.

For developers working on Linux, Swift 6 introduces a fully static SDK, enabling the creation of statically linked executables with no external dependencies.

🔧 Foundation Library Revamped 🔧

Swift 6 unifies the Foundation library across platforms, ensuring consistency and performance, especially on Linux and Windows. Core types like JSONDecoder, URL, and FileManager have been completely reimplemented in Swift, offering a new level of reliability across platforms.

If you’re working on cross-platform apps, this new Foundation implementation ensures your code behaves consistently across all Swift-supported platforms.