title: swift - how use FIRE() in NSTimer
body: <p>I need a cycle of 5 times of 2.5 seconds in a single cycle, however, that the pressure of a button bait from single cycle without interrupting the scheduling.
  I use method fire (with pressed button) for stoping a repeating timer without interrupting its regular firing schedule, but I don't know, subsequent cycles are shorter than the defined 2.5 seconds:</p>
  
  <p>.......</p>
  
  <pre><code>@IBAction func buttonZeroPressed(sender: AnyObject) {
  
      timer.fire()
      ++addWin
  }
  </code></pre>
  
  <p>......</p>
  
  <pre><code>timer = NSTimer.scheduledTimerWithTimeInterval(2.5, target: self,
          selector: Selector("levelOne"), userInfo:nil,repeats: true)
  </code></pre>
  
  <p>......</p>
  
  <pre><code>func levelOne() {
  
      level = 1
      count++
      changePhoto()
      if (count  &gt;= 5) {
          timer.invalidate()
         }
  }
  </code></pre>
  
  <p>After the 3 pressed button, the timer seems to be 2.5 seconds, and I do not understand why!</p>