Color ouput with Swift command line tool

问题

I'm writing a command line tool with Swift and I'm having trouble displaying colors in my shell. I'm using the following code:

println("\033[31;32mhey\033[39;39m")

or even

NSFileHandle.fileHandleWithStandardOutput().writeData("\033[31;32mhey\033[39;39m".dataUsingEncoding(NSASCIIStringEncoding, allowLossyConversion: true)!)

It works when I use a simple echo in php (the text is displayed in green) but is there a reason it doesn't work in a Swift command line tool?

Thanks!

回答1:

Swift has built in unicode support. This invalidates using of back slash. So that I use color codes with "\u{}" syntax. Here is a println code which works perfectly on terminal.

// \u{001B}[\(attribute code like bold, dim, normal);\(color code)m

// Color codes
// black   30
// red     31
// green   32
// yellow  33
// blue    34
// magenta 35
// cyan    36
// white   37

println("\u{001B}[0;33myellow")

Hope it helps.

回答2:

Based on @cyt answer, I've written a simple enum with these colors and also overloaded + operator so you can print using that enum.

It's all up on Github, but it's really that simple:

enum ANSIColors: String {
    case black = "\u{001B}[0;30m"
    case red = "\u{001B}[0;31m"
    case green = "\u{001B}[0;32m"
    case yellow = "\u{001B}[0;33m"
    case blue = "\u{001B}[0;34m"
    case magenta = "\u{001B}[0;35m"
    case cyan = "\u{001B}[0;36m"
    case white = "\u{001B}[0;37m"

    func name() -> String {
        switch self {
        case .black: return "Black"
        case .red: return "Red"
        case .green: return "Green"
        case .yellow: return "Yellow"
        case .blue: return "Blue"
        case .magenta: return "Magenta"
        case .cyan: return "Cyan"
        case .white: return "White"
        }
    }

    static func all() -> [ANSIColors] {
        return [.black, .red, .green, .yellow, .blue, .magenta, .cyan, .white]
    }
}

func + (let left: ANSIColors, let right: String) -> String {
    return left.rawValue + right
}

// END


// Demo:

for c in ANSIColors.all() {
    println(c + "This is printed in " + c.name())
}

回答3:

You can use Rainbow if you don't mind using it as a framework.

import Rainbow
print("Red text".red)
print("Yellow background".onYellow)
print("Light green text on white background".lightGreen.onWhite)

https://github.com/onevcat/Rainbow

回答4:

Combining some of @Diego's answer, you can use Swift's new DefaultStringInterpolation structure to extend this decoration into your string literals–

enum ASCIIColor: String {
    case black = "\u{001B}[0;30m"
    case red = "\u{001B}[0;31m"
    case green = "\u{001B}[0;32m"
    case yellow = "\u{001B}[0;33m"
    case blue = "\u{001B}[0;34m"
    case magenta = "\u{001B}[0;35m"
    case cyan = "\u{001B}[0;36m"
    case white = "\u{001B}[0;37m"
    case `default` = "\u{001B}[0;0m"
}

extension DefaultStringInterpolation {
    mutating func appendInterpolation<T: CustomStringConvertible>(_ value: T, color: ASCIIColor) {
        appendInterpolation("\(color.rawValue)\(value)\(ASCIIColor.default.rawValue)")
    }
}
// USAGE:
// "\("only this string will be green!", color: .green)"

回答5:

Expanding upon Diego Freniche's answer we can incorporate the functionality of Rainbow, as referenced in Uncharted Works's Answer, without needing to import the framework itself using a simple String extension:

enum ANSIColor: String {

    typealias This = ANSIColor

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

    static var values: [This] {
        return [.black, .red, .green, .yellow, .blue, .magenta, .cyan, .white, .default]
    }

    static var names: [This: String] = {
        return [
            .black: "black",
            .red: "red",
            .green: "green",
            .yellow: "yellow",
            .blue: "blue",
            .magenta: "magenta",
            .cyan: "cyan",
            .white: "white",
            .default: "default",
        ]
    }

    var name: String {
        return This.names[self] ?? "unknown"
    }

    static func + (lhs: This, rhs: String) -> String {
        return lhs.rawValue + rhs
    }

    static func + (lhs: String, rhs: This) -> String {
        return lhs + rhs.rawValue
    }

}

extension String {

    func colored(_ color: ANSIColor) -> String {
        return color + self + ANSIColor.default
    }

    var black: String {
        return colored(.black)
    }

    var red: String {
        return colored(.red)
    }

    var green: String {
        return colored(.green)
    }

    var yellow: String {
        return colored(.yellow)
    }

    var blue: String {
        return colored(.blue)
    }

    var magenta: String {
        return colored(.magenta)
    }

    var cyan: String {
        return colored(.cyan)
    }

    var white: String {
        return colored(.white)
    }

}

来源：https://stackoverflow.com/questions/27807925/color-ouput-with-swift-command-line-tool