Argument Parser Library for Swift
Article Summary
Nate Cook from Apple's Swift team just made building command-line tools in Swift genuinely enjoyable. The new ArgumentParser library turns 50 lines of code into a fully-featured CLI with subcommands, validation, and auto-generated help screens.
Apple open-sourced ArgumentParser, a Swift library that eliminates the boilerplate of parsing command-line arguments. Using property wrappers and Swift's type system, it automatically generates help text, validates inputs, and handles complex command structures. The Swift project is already adopting it across their toolchain.
Key Takeaways
- Property wrappers (@Argument, @Option) automatically parse and validate CLI inputs
- Type-safe parsing: define Int property, get automatic validation with zero casting
- Subcommands work like Git: nest types, list in config, done
- Auto-generates help screens and error messages from your type declarations
- Full CLI tool in under 50 lines including validation and documentation
Critical Insight
ArgumentParser uses Swift's type system to build command-line interfaces declaratively, cutting boilerplate while adding automatic validation and help generation.
