Scripting

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Swift Scripting

Getting started

The first step is to add this to the top of your Swift script:

#!/usr/bin/swift

The second step is to make it executable

$ chmod +x script.swift

What IDE to use

For simple scripts, Xcode Playgrounds are a great IDE. Your code runs the same way it would in the command line, you get autocomplete, live previews and a console output.

For more complex scripts, it is possible to hack Atom into a Swift scripting IDE with the following package installs:

$ apm install script language-swift

Adding frameworks

Third party libraries need to be compiled as dynamic frameworks - this can be achieved manually or with Carthage or Cocoapods (via the Rome plugin).

To include in your script, you need to specify a target and a framework path in your shebang

#!/usr/bin/swift -target x86_64-macosx10.12 -F /Library/Frameworks -F Rome

Launch arguments and user input

You can access launch arguments using:

CommandLine.arguments

You can ask for user input using:

let string = readLine()

Shell

You can run shell commands using Process() (formerly NSTask) using this function (make sure to import Foundation).

func shell(_ command: String) {
    let arguments = command.components(separatedBy: " ")
    let process = Process()
    process.launchPath = "/usr/bin/env"
    process.arguments = arguments
    process.waitUntilExit()
    process.launch()
}

Current file path

There's no NSBundle when writing a Swift script. To get the current path use

let currentPath = FileManager.default.currentDirectoryPath

Returning

You can't return in a Swift script. To end the context, use:

exit(1)

Color

You can format a line by adding color using the following struct:

struct commandLineFormat {
    static let black = "\u{001B}[0;30m"
    static let red = "\u{001B}[0;31m"
    static let green = "\u{001B}[0;32m"
    static let yellow = "\u{001B}[0;33m"
    static let blue = "\u{001B}[0;34m"
    static let magenta = "\u{001B}[0;35m"
    static let cyan = "\u{001B}[0;36m"
    static let white = "\u{001B}[0;37m"
}

Advanced Shell

The function breaks down a command into a string array of arguments by separating on " ". This is somewhat hacky as there are actual spaces you might want to keep.

Additionally, you may wish to capture the output from the process.

Here is an advanced example:

let shellSeparator = "␣"

func shell(_ command: String) -> String {
    var arguments = command.components(separatedBy: " ")
    arguments = arguments.map{ $0.replacingOccurrences(of: shellSeparator, with: " ")}
    let pipe = Pipe()
    let process = Process()
    process.launchPath = "/usr/bin/env"
    process.arguments = arguments
    process.standardOutput = pipe
    process.waitUntilExit()
    process.launch()
    let data = pipe.fileHandleForReading.readDataToEndOfFile()
    return String(data: data, encoding: String.Encoding.utf8)
}