What are the notable improvements in Xcode 16?

Xcode 16 introduces several notable improvements that enhance the development experience across various stages of app creation:

Code Completion: Xcode 16 features an innovative code completion engine powered by a model specifically trained for Swift and Apple SDKs. This engine uses project symbols to customize suggestions and runs locally on your Mac, ensuring privacy and fast results, even offline.
Swift 6: A new language mode in Swift 6 provides concurrency safety guarantees, turning data races into compile-time issues, which improves code correctness and safety.
Previews: Xcode Previews have been enhanced with a new dynamic linking architecture, using the same build artifacts for both previews and when you build and run, which streamlines the workflow. Additionally, a new previewable macro allows for dynamic properties like state to be used directly in previews.
Builds: The introduction of explicit modules improves parallelism, diagnostics, and debugging without requiring code changes. For C and Objective-C, this feature is enabled by default, while Swift requires opting in.
Swiftassist: A new companion tool, Swiftassist, helps with coding tasks by answering questions and assisting with API experimentation. It runs in the cloud but ensures privacy by not storing code on the server.
Instruments and Debugging: Xcode 16 includes a flame graph for profiling data, providing deeper insights into app performance. Enhancements to localization workflows and a single view of backtraces also contribute to improved productivity and app quality.

These improvements make Xcode 16 a powerful tool for developers, offering enhanced performance, safety, and productivity features. For more details, you can refer to the session What’s new in Xcode 16.