title: What happens to my NSRunLoop and timer when the app goes into background and returns?
body: <p>I have an <code>NSRunLoop</code> in my app connected to a timer:</p>
  
  <pre><code>NSTimer *updateTimer = [NSTimer scheduledTimerWithTimeInterval:300 target:self selector:@selector(onUpdateTimer) userInfo:nil repeats:YES];
  [[NSRunLoop mainRunLoop] addTimer:updateTimer forMode:NSRunLoopCommonModes];
  </code></pre>
  
  <p>When the app goes into background, what happens to this runloop?  Does it disappear, meaning I should recreate it in <code>applicationDidBecomeActive:</code>?</p>