title: Swift: label text --> "fatal error: unexpectedly found nil while unwrapping an Optional value"
body: <p>like it says in the title, i am trying to change label text upon click of a button. Error appears at line <code>self.playerChoice.text = "You: Rock"</code></p>
  
  <pre><code>import UIKit
  
  class ViewController: UIViewController {
  
  var player : Int = Int()
  
  @IBOutlet weak var readyLabel: UILabel!
  
  @IBAction func noButton(sender: AnyObject) {
      exit(0)
  }
  
  // ---------------------------------------------------------
  
  @IBOutlet var computerChoice: UILabel!
  
  @IBOutlet var playerChoice: UILabel!
  
  @IBOutlet var score: UILabel!
  
  
  // Variables -------------------------------------------------
  
  let Rock : String = "Rock"
  let Paper : String = "Paper"
  let Scissors : String = "Scissors"
  
  //------------------------------------------------------------
  
  
  
  override func viewDidLoad() {
      super.viewDidLoad()
      // Do any additional setup after loading the view, typically from a nib.
  
      }
  
  
  // ----------------------------------------------------------------
  
  @IBAction func rockButton(rockbut: UIButton) {
  
      player = 0
      var ai = arc4random_uniform(3)
      self.playerChoice.text = "You: Rock"
  
      }
  
  @IBAction func paperButton(paperbut: UIButton) {
  
      player = 1
      var ai = arc4random_uniform(3)
      self.playerChoice.text = "You: Paper"
  
      }
  
  @IBAction func scissorsButton(scissorsbut: UIButton) {
  
      player = 2
      var ai = arc4random_uniform(3)
      self.playerChoice.text = "You: Scissors"
  
          }
      }
  </code></pre>