NSUserUnixTaskでJXAスクリプトを実行して結果を得る

DoShellScript.swift

#!/usr/bin/env swift

import Cocoa

guard let pathToMe = URL(string: "\(#file)", relativeTo: URL(fileURLWithPath: FileManager.default.currentDirectoryPath))?.path else {
  print("Error: current path of #file")
  exit(-1)
}
let __file__ = pathToMe as NSString

let scriptsPath = "\(__file__.deletingLastPathComponent)/DoShellScript.js"
let scriptsURL = URL(fileURLWithPath: scriptsPath)
guard let task = try? NSUserUnixTask(url: scriptsURL) else {
  print("Error: task is nil")
  exit(-2)
}
let stdout = Pipe()
let stderr = Pipe()
task.standardOutput = stdout.fileHandleForWriting
task.standardError = stderr.fileHandleForWriting
task.execute { error in
  if let error = error {
    print(error.localizedDescription)
    exit(-3)
  }
  let outdata = stdout.fileHandleForReading.readDataToEndOfFile()
  let errdata = stderr.fileHandleForReading.readDataToEndOfFile()
  stdout.fileHandleForReading.closeFile()
  stderr.fileHandleForReading.closeFile()
  let out = (String(data: outdata, encoding: .utf8) ?? "").trimmingCharacters(in: .whitespacesAndNewlines)
  let err = (String(data: errdata, encoding: .utf8) ?? "").trimmingCharacters(in: .whitespacesAndNewlines)
  print("stdout:\n\(out)")
  print("stderr:\n\(err)")
  NSApplication.shared().terminate(nil)
}
NSApplication.shared().run()

DoShellScript.js

#!/usr/bin/osascript
delay(3) //歯車アイコン確認用
App = Application.currentApplication()
App.includeStandardAdditions = true
App.doShellScript('ls ~/', {alteringLineEndings:false})

DoShellScript.swift と DoShellScript.js を同ディレクトリに置き実行。結果は以下の通り。

$ DoShellScript.swift 
stdout:
Applications
Desktop
Documents
Downloads
Library
Movies
Music
Pictures
Projects
Public
Sites
stderr: