build system
Asked on 06/17/2025
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Apple's WWDC sessions have introduced several updates and improvements to the build system, particularly focusing on explicitly built modules. Here are some key points from the sessions:
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Explicitly Built Modules: This approach allows the build system to have better control over module build tasks, optimizing the build pipeline. It improves build efficiency and reliability by providing precise and deterministic sharing of modules. This also enhances the speed of debugging Swift code as the debugger can reuse already built modules. For more details, you can refer to the session Demystify explicitly built modules.
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Swift Build: Apple has open-sourced Swift Build, a powerful and extensible build engine used by Xcode and Swift Playground. This is part of an effort to unify the build experience across Swift Open Source Toolchains and Xcode. You can learn more about this in the session What’s new in Xcode.
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Build System Improvements in Xcode 16: Xcode 16 introduces explicit modules, which provide improved parallelism, better diagnostics, and faster debugging without changing any code. For C and Objective-C, explicit modules are enabled by default, while for Swift, you need to opt-in. More information can be found in the session What’s new in Xcode 16.
These updates are designed to make the build process more efficient and reliable, providing developers with better tools to manage and optimize their build tasks.
What’s new in Xcode
Discover the latest productivity and performance advancements in Xcode 26. Learn how to leverage large language models in your development workflow. Explore editing and debugging enhancements, improved performance and testing tools, and Swift Build - the open-source build system engine used by Xcode.
Demystify explicitly built modules
Explore how builds are changing in Xcode 16 with explicitly built modules. Discover how modules are used to build your code, how explicitly built modules improve transparency in compilation tasks, and how you can optimize your build by sharing modules across targets.
What’s new in Swift
Join us for an update on Swift. We’ll talk about workflow improvements that make you more productive, and new and modernized library APIs for fundamental programming tasks. We’ll show examples of Swift adoption throughout more layers of the software stack. Finally, we’ll explore new language features for both improving approachability of concurrency, and achieving peak performance when you need it.