Whats new in Xcode16?

Xcode 16 introduces several new features and improvements across various aspects of app development. Here are some of the key updates:

1. Code Completion:

   • Xcode 16 features a new code completion engine that provides more thorough suggestions. This engine is powered by an on-device coding model specifically trained for Swift and Apple SDKs, utilizing the surrounding code context to enhance productivity. This feature is available when running Xcode 16 on macOS Sequoia.
   • The new engine can predict the code you need, using your project symbols to customize suggestions. It runs locally on your Mac, ensuring privacy and fast results, even when offline.

2. Swift 6:

   • Swift 6 introduces a new language mode that provides concurrency safety guarantees, turning data races into compile-time issues, which improves code correctness and safety.
   • Xcode 16 includes warnings for concurrency issues, helping developers adopt these new safety features before fully switching to Swift 6.

3. Previews:

   • Previews in Xcode 16 are faster due to a new execution engine and improvements in the compiler and build system. The new dynamic linking architecture uses the same build artifacts for previews and when you build and run, avoiding the need for separate builds.
   • New APIs, such as the previewable macro, make previews simpler to write, more reusable, and better integrated with your model.

4. Builds:

   • Xcode 16 introduces explicit modules, which improve parallelism, diagnostics, and debugging without changing any code. This feature is on by default for C and Objective-C and can be enabled for Swift in the build settings.
   • Improvements to Swift package integration allow for more efficient build processes.

5. Debugging and Performance:

   • Xcode 16 includes a single view of backtraces showing relevant code from all stack frames together.
   • A new flame graph in Instruments provides deeper insights into app performance, helping to identify and resolve performance issues more effectively.

6. Swiftassist:

   • Swiftassist is a new companion tool for coding tasks, powered by a larger and more powerful model that runs in the cloud. It can answer coding questions and help with tasks like experimenting with new APIs.

7. Localization and Other Enhancements:

   • Enhancements to localization catalogs make it easier to bring apps to more people around the world.
   • Other improvements include a hardened C runtime and better workflows for various development tasks.

For more detailed information, you can refer to the session What’s new in Xcode 16 and the Platforms State of the Union.