title: How to use NSComparator?
body: <p>I would like to know if the below question is possible using <code>NSComparator</code> or not?</p>
  
  <p>I have two arrays; both hold data models. I have a property named rank in the data model. Now I want to compare both arrays and want to know if one of them holds higher ranked data models. 
  If Yes I would like to get <code>NSComparisonResult = NSOrderedAscending</code>. </p>
  
  <p>By the way I'm using another approach here: is "total of each data Model's rank in array and if the total is greater than second array's data Model's total rank."</p>