title: How to use PFQuery to query for exact match to array?
body: <p>I have a <code>Game</code> class in Parse, and one of the attributes is <code>participants</code>,  which is an array of <code>NSStrings</code> usernames. My goal is to perform a PFQuery based on an NSArray of username (called <code>selectedParticipants</code>), so that a Game object is returned if there is an exact match of usernames found <code>participants</code>. </p>
  
  <p>However, when I use</p>
  
  <pre><code>[queryForGames whereKey:@"participants" equalTo:selectedParticipants];
  </code></pre>
  
  <p>I get an error that I am unable to do a comparison query based on Arrays (<code>Cannot do a comparison query for type: __NSArrayM</code>).  I have also tried several other types of query listed in the Parse <a href="http://parse.com/docs/osx/api/Classes/PFQuery.html" rel="nofollow">reference</a> guide, such as using <code>whereKey:containsAllObjectsInArray:</code>, but they will return extraneous <code>Game</code> objects that contains usernames addition to those in <code>equalTo:selectedParticipants</code>. Is there a way where I could query by an exact match of arrays using PFQuery?</p>
  
  <p>Thanks!</p>