title: Core data dataModel issue in iOS
body: <p>I am new to coredata, using it for the first time in an <a href="/questions/tagged/ios" class="post-tag" title="show questions tagged &#39;ios&#39;" rel="tag">ios</a> application project,
  and have no idea how to add entities with relations. The scenario is this:</p>
  
  <p>There is an Order(entity) -> has multiple Vendors(entity) ->every vendor has multiple Items(entity)</p>
  
  <p>How to design this thing? Can anyone share a good tutorial, example for above mentioned thing?</p>