title: How to get an NSTimer to stop repeating after a condition is met
body: <p>I have two NSTimers that I programmed to make a button appear on the screen and then disappear. How can I program it to stop adding and removing buttons once a condition is met?</p>
  
  <p>Here is my code:</p>
  
  <pre><code>   var timerRemoveButton = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: "removeButton", userInfo: nil, repeats: true)
     var timerAddButton = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: "addButton", userInfo: nil, repeats: true)
  </code></pre>