title: minimizing parse requests while looping through array
body: <p>I'm working on a pet project using parse as a back end. I'm setting up a viewcontroller that contains a list of people you can possibly add as "friends"; these are people that 
  a) exist in your contacts list and 
  b) have already downloaded the app and signed up. </p>
  
  <p>Different buttons will be displayed depending on their status as a user (invite button if they only exist in your contacts list, add to friends button if they're also using the app already).</p>
  
  <p>I'm trying to keep my Parse account to 30 requests/second so that I'm not out of pocket for a pet app. </p>
  
  <p>One way I've thought to figure out who is registered as a user AND who exists in my contacts list is to loop through the contacts list on my phone and query that phone number on parse. However, this would obviously go over my limit on requests/second.</p>
  
  <p>Is there a way (I've looked through Parse documentation and googled it) to take an array (list of contacts on my phone) and run a PFQuery ON THAT ARRAY, checking each object and returning matches?</p>