I was interested in performing system calls from Swift, and I found a resource that I had to modify somewhat. I imagine that the language has changed since that post was written. At any rate, here is the working code,

#!/usr/bin/env xcrun swift

import Foundation

let task = NSTask()
task.launchPath = "/bin/ls"
task.arguments = ["-alh"]

let pipe = NSPipe()
task.standardOutput = pipe
task.launch()

let data = pipe.fileHandleForReading.readDataToEndOfFile()
let output: NSString = NSString( data: data, encoding: NSUTF8StringEncoding )!

print( output )

Two things stood out to me: line 6 requires the full path of the ls command, which is probably a performance thing, and the NSString call at line 14 requires the encoding, which seems like a real pain to remember to type out all the time.