An instance of a view in ios - ios

Question

I'm having a difficulty understanding what output.text means. I think my understanding is that output is an instance of the class UIViewController and text is a variable defined in this class. Is this correct? Also, in the function, consoleOut(), why should one do output.text = output.text + text instead of output.text = text?
//
// ViewController.swift
// Guessing Game
//
// Created by Jae Hyun Kim on 8/6/15.
// Copyright (c) 2015 Jae Hyun Kim. All rights reserved.
//
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var inputField: UITextField!
#IBOutlet weak var output: UITextView!
var guesses : UInt = 0;
var number : UInt = 0;
var gameover = false;
let MAX_GUESSES = 8;
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func consoleOut(text : String) {
output.text = output.text + text;
}
#IBAction func guess(sender: UIButton) {
}
}

Answer 1

output is a UITextView that is defined in the view (the file that shows what screen will appear to the user). So you are correct in saying that text is a variable of the UITextView class.
Additionally, output.text = output.text + text will append text to the existing text in output.text. This is unlike output.text = text which will overwrite whatever was already in output.text with the new text.