title: Error - Thread 1: signal SIGABRT (unrecognized selector sent to instance)
body: <p>I'm making an app where you need to indicate the amount of time that a label appears for and that amount of time is counted down at the bottom of the page.</p>
  
  <p>When I run my app on the Xcode simulator, the <code>chronometre</code> label displays "Optional (*indicated number)" when I want it to only display the indicated number. Once it's displayed for a second, I get taken to my App Delegate and it says <code>Thread 1: signal SIGABRT</code>.</p>
  
  <p>The following error is also shown: <code>2015-02-22 21:05:50.860 MemoPres.New[71008:12980314] -[MemoPres_New.ViewController subtractTime:]: unrecognized selector sent to instance 0x7fbab24299c0
  2015-02-22 21:05:50.862 MemoPres.New[71008:12980314] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[MemoPres_New.ViewController subtractTime:]: unrecognized selector sent to instance 0x7fbab24299c0'</code>.</p>
  
  <p>Help would be greatly appreciated.</p>
  
  <p>The following is all of my code:</p>
  
  <pre><code>class ViewController: UIViewController {
  
  
  @IBOutlet weak var chronometre: UILabel!
  @IBOutlet weak var prochainpointLabel: UILabel!
  @IBOutlet weak var pointactuelLabel: UILabel!
  @IBOutlet weak var point1Textfield: UITextField!
  @IBOutlet weak var point1tempsTextfield: UITextField!
  @IBOutlet weak var point2Textfield: UITextField!
  @IBOutlet weak var point2tempsTextfield: UITextField!
  
  
  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.
  }
  
  @IBAction func presenterButton(sender: AnyObject) {
  
      var timer = NSTimer()
      var seconds = point1tempsTextfield.text.toInt()
  
      pointactuelLabel.text = point1Textfield.text
      prochainpointLabel.text = point2Textfield.text
      chronometre.text = "\(seconds)"
  
  
  
          timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: ("subtractTime:"), userInfo: nil, repeats: true)
  
  
  
      func subtractTime(dt:NSTimer){
          seconds!--
          chronometre.text = "\(seconds)"
  
      }
  
  
          }
  }
  </code></pre>