title: Updating UILabel.text is slow
body: <p>Right now, my view controller is doing some very simple things:</p>
  
  <ol>
  <li>Call a web service</li>
  <li>Println a value</li>
  <li>Set a UILabel's text value to that value</li>
  </ol>
  
  <p>1 &amp; 2 are pretty snappy.  The third step takes about 10 seconds to appear on screen in the simulator.</p>
  
  <pre><code>        switch currentTemp {
      case 80..&lt;180:
          self.riskType.text = "Heat Index:"
          self.perceivedTemperatureValue.text = "\(currentHeatIndex)"
      case -100..&lt;50:
          self.riskType.text = "Wind Chill:"
          self.perceivedTemperatureValue.text = "\(currentWindChill)"
      default:
          self.riskType.text = "Temperature:"
          println(currentTemp)
          self.perceivedTemperatureValue.text = "\(currentTemp)"
      }
  </code></pre>
  
  <p>Any idea why this is so slow?  Is there something else I need to do to make the change appear as soon as I println the value?</p>