Swift script to extract all string literals from a Swift source file in the format of a Localizable.strings file

xstrings.swift

#!/usr/bin/swift
import Foundation

func processFile(_ path: String, keyPrefix: String?) {
    guard let file = freopen(path, "r", stdin) else {
        fputs("Failed to open file.\n", stderr)
        return
    }
    defer {
        fclose(file)
    }

    let pattern = #""(?:\.|[^"])*""#
    let regex = try! NSRegularExpression(pattern: pattern)

    var keyCount = 0
    let keyPrefix = keyPrefix ?? "key"

    while let line = readLine() {
        let range = NSRange(location: 0, length: line.utf16.count)

        regex.enumerateMatches(in: line, range: range) { result, _, _ in
            guard let match = result,
                  let range = Range(match.range, in: line) else { return }
            print("\"\(keyPrefix).\(keyCount)\" = \(line[range]);")
            keyCount += 1
        }
    }
}

func run() {
    guard CommandLine.arguments.count > 1 else {
        fputs("Syntax: xstrings <filename> [<key prefix>]\n", stderr)
        return
    }

    let keyPrefix: String? =  CommandLine.arguments.count > 2 ? CommandLine.arguments[2] : nil
    processFile(CommandLine.arguments[1], keyPrefix: keyPrefix)
}

run()

Use python man.

Use python man.

No doubt that Python, Ruby, Perl or similar would be a better choice for this, but since I don't know any of those well enough it would have taken me longer than doing it in Swift. The benefit of Swift is that you can also compile to a binary executable.