title: How to transfer data ViewControllers/classes using NSNotificationCenter?
body: <p>I have a table view controller that is supposed to be populated with data from an array that is encapsulated within a <code>store</code> class. The table needs to know how many rows are in each section via the method <code>table:numberOfRowsInSection:</code>. In this method, I need to return the size of the array that is inside my instance of <code>store</code>. I initially did this by making <code>store</code> a singleton, but was told this was inefficient and that using NSNotificationCenter would be better. </p>
  
  <p>As far as I know, all NSNotificationCenter does is trigger methods in certain objects when another object posts a specific notification. How can I use NSNotificationCenter to send the size of the array to my table view controller? </p>