title: Add 'addObserver' (NSNotificationCenter ) in a 1st view controller, handle in 2nd
body: <p>I saw a few examples about adding observer and handle in the same class, but what I want to know is if it's possible to add observer in first view controller and handle it in second view controller?</p>
  
  <p>I want constantly send distance from first view controller and handle it in the 2nd one.
  The 2nd view controller added as a sub view: <code>addSubview</code>, <code>addChildViewController</code>.</p>
  
  <p>It's something like broadcast in android.</p>