title: How to add observer on NSMutableArray?
body: <p>I have searched a lot but didn't find useful code or tutorial.</p>
  
  <p>In my application, I have an mutable array which update in every 60 seconds.</p>
  
  <p>The objects in array is being displayed by table view in multiple view controllers.</p>
  
  <p>I want to reload table view automatically when only when values in array changes or updated.</p>
  
  <p>For this, I want to add observer on mutable array i.e when values in array changes then it should call a particular method for e.g </p>
  
  <pre><code>-(void)ArrayUpdatedNotification:(NSMutableArray*)array
  {
      //Reload table or do something
  } 
  </code></pre>
  
  <p>Thanks in advance.</p>