title: Handle many-to-many relations in CloudKit
body: <p>I'm trying to create a tagging system using CloudKit.
  I have a type called Article and an tag type called Tag.
  Each article can have multiple tags applied. I want my data to be normalied so since same tags can appear on several articles and articles can have multiple tags, I need a many-to-many relation.
  In old school DB-stuff this would require a junction table.</p>
  
  <p>How do you do that in CloudKit? </p>
  
  <p>In any of Apples documentation I can only find examples of one-to-many relations.</p>
  
  <p>So I have created a junction-table type called ArticleTag, that consists og two CKReferences. One for the Article reference and one for the Tag reference.</p>
  
  <p>This should work, but what is the best way to query for tags per article?</p>
  
  <p>Kind regards,
  Esben</p>