ArgumentParser.md

ArgumentParser

Straightforward, type-safe argument parsing for Swift.

Overview

By using ArgumentParser, you can create a command-line interface tool by declaring simple Swift types. Begin by declaring a type that defines the information that you need to collect from the command line. Decorate each stored property with one of ArgumentParser's property wrappers, declare conformance to ParsableCommand, and implement your command's logic in its run() method.

import ArgumentParser

@main
struct Repeat: ParsableCommand {
    @Argument(help: "The phrase to repeat.")
    var phrase: String

    @Option(help: "The number of times to repeat 'phrase'.")
    var count: Int? = nil

    mutating func run() throws {
        let repeatCount = count ?? 2
        for _ in 0..<repeatCount {
            print(phrase)
        }
    }
}

When a user executes your command, the ArgumentParser library parses the command-line arguments, instantiates your command type, and then either calls your run() method or exits with a useful message.

Additional Resources

• ArgumentParser on GitHub
• ArgumentParser on the Swift Forums

Topics

Essentials

• doc:GettingStarted
• ParsableCommand
• AsyncParsableCommand
• doc:CommandsAndSubcommands
• doc:CustomizingCommandHelp

Arguments, Options, and Flags

• doc:DeclaringArguments
• Argument
• Option
• Flag
• OptionGroup
• ParsableArguments

Property Customization

• doc:CustomizingHelp
• ArgumentHelp
• ArgumentVisibility
• NameSpecification

Custom Types

• ExpressibleByArgument
• EnumerableFlag

Validation and Errors

• doc:Validation
• ValidationError
• CleanExit
• ExitCode

Shell Completion Scripts

• doc:InstallingCompletionScripts
• doc:CustomizingCompletions
• CompletionKind

Advanced Topics

• doc:ManualParsing
• doc:ExperimentalFeatures