NSTask是用于将另一个程序作为子进程运行的类。您可以捕获程序的输出，错误输出，退出状态等等。
扩展我对xpre 6 swiftsystem（）命令的回答，这是一个简单的实用函数，用于同步运行命令，并返回输出，错误输出和退出代码（现已针对Swift 2更新）：
func runCommand(cmd : String, args : String...) -> (output: [String], error: [String], exitCode: Int32) { var output : [String] = [] var error : [String] = [] let task = NSTask() task.launchPath = cmd task.arguments = args let outpipe = NSPipe() task.standardOutput = outpipe let errpipe = NSPipe() task.standardError = errpipe task.launch() let outdata = outpipe.fileHandleForReading.readDataToEndOfFile() if var string = String.fromCString(UnsafePointer(outdata.bytes)) { string = string.stringByTrimmingCharactersInSet(NSCharacterSet.newlineCharacterSet()) output = string.componentsSeparatedByString("n") } let errdata = errpipe.fileHandleForReading.readDataToEndOfFile() if var string = String.fromCString(UnsafePointer(errdata.bytes)) { string = string.stringByTrimmingCharactersInSet(NSCharacterSet.newlineCharacterSet()) error = string.componentsSeparatedByString("n") } task.waitUntilExit() let status = task.terminationStatus return (output, error, status)}用法示例：
let (output, error, status) = runCommand("/usr/bin/git", args: "status")print("program exited with status (status)")if output.count > 0 { print("program output:") print(output)}if error.count > 0 { print("error output:") print(error)}或者，如果您仅对输出感兴趣，而不对错误消息或退出代码感兴趣：
let output = runCommand("/usr/bin/git", args: "status").output输出和错误输出以字符串数组形式返回，每行一个字符串。
的第一个参数
runCommand()必须是可执行文件的完整路径，例如
"/usr/bin/git"。您可以使用外壳程序启动程序（
system()也可以这样做）：
let (output, error, status) = runCommand("/bin/sh", args: "-c", "git status")优点是可以通过默认搜索路径自动找到“ git”可执行文件。缺点是，如果参数包含空格或其他在Shell中具有特殊含义的字符，则必须正确引用/转义参数。
Swift 3 更新 ：
func runCommand(cmd : String, args : String...) -> (output: [String], error: [String], exitCode: Int32) { var output : [String] = [] var error : [String] = [] let task = Process() task.launchPath = cmd task.arguments = args let outpipe = Pipe() task.standardOutput = outpipe let errpipe = Pipe() task.standardError = errpipe task.launch() let outdata = outpipe.fileHandleForReading.readDataToEndOfFile() if var string = String(data: outdata, encoding: .utf8) { string = string.trimmingCharacters(in: .newlines) output = string.components(separatedBy: "n") } let errdata = errpipe.fileHandleForReading.readDataToEndOfFile() if var string = String(data: errdata, encoding: .utf8) { string = string.trimmingCharacters(in: .newlines) error = string.components(separatedBy: "n") } task.waitUntilExit() let status = task.terminationStatus return (output, error, status)}
