Does something like python's raw_input exist in swift?

To assign the content of a UITextFieldsingle you have to use the property text:

import UIKit
class ViewController: UIViewController {
    @IBOutlet weak var textField: UITextField!
    // otros métodos y variables

    @IBAction func buttonClicked(sender: AnyObject) {
        let valorIngresado = textField.text;
    }
}

If what you want is to execute a script in the console, there is no method to directly read a value from the keyboard, but it is possible to implement it in the following way:

// Archivo script.swift
#!/usr/bin/env xcrun swift
import Foundation

// Esta función se encarga de leer desde la entrada estándar (teclado)
// Y regresa el dato como una cadena
func readLine() -> String {
    let keyboard = NSFileHandle.fileHandleWithStandardInput()
    let inputData = keyboard.availableData
    return NSString(data: inputData, encoding:NSUTF8StringEncoding) as! String
}

let cadena = readLine()
print(cadena)

And run it with

$ ./script.swift

You need to run this example as a script, it doesn't work in playgrounds.

Code to read from keyboard originally appears here

I see I can do something like this to use it with Xcode:

let dato = UITextField(frame: CGRect(x:0, y: 0, width: 50, height: 30))

dato.placeholder = "Introduzca un valor"

In this way I formulate what I want to ask in it textfield. Although for console it is not worth clear.

In this way I get it to work for me from the same Xcode and I can enter the value without error through the console, it is practically the same code as the previous one but changing a few things.

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