Input from the keyboard in command line application

It's actually not that easy, you have to interact with the C API. There is no alternative to scanf. I've build a little example:

main.swift

import Foundation

var output: CInt = 0
getInput(&output)

println(output)

UserInput.c

#include <stdio.h>

void getInput(int *output) {
    scanf("%i", output);
}

cliinput-Bridging-Header.h

void getInput(int *output);

I managed to figure it out without dropping down in to C:

My solution is as follows:

func input() -> String {
    var keyboard = NSFileHandle.fileHandleWithStandardInput()
    var inputData = keyboard.availableData
    return NSString(data: inputData, encoding:NSUTF8StringEncoding)!
}

More recent versions of Xcode need an explicit typecast (works in Xcode 6.4):

func input() -> String {
    var keyboard = NSFileHandle.fileHandleWithStandardInput()
    var inputData = keyboard.availableData
    return NSString(data: inputData, encoding:NSUTF8StringEncoding)! as String
}

The correct way to do this is to use readLine, from the Swift Standard Library.

Example:

let response = readLine()

Will give you an Optional value containing the entered text.