title: core data how to filter (NSPredicate) including a relationship requirement and given the relationship object?
body: <p>How would I filter (construct an NSPredicate) for the following.</p>
  
  <ul>
  <li>Have a SCHOOL and PERSON entities</li>
  <li>One-to-many relationship, i.e. a PERSON has one SCHOOL, SCHOOL has many PERSONs</li>
  <li>Input to the filter method are (a) persons Name (e.g. all with a first name of "Tom") , and (b) the managed object of the School itself.  </li>
  <li>for the purposes of this question assume School has no unique attributes</li>
  </ul>
  
  <p>So then my confusion/observations are:</p>
  
  <ul>
  <li>I already have the School managed object itself, however not sure how to use this when creating the predicate?</li>
  <li>But if I create the NSPredicate how do I create the relationship to the SCHOOL in any case, as there are no IDs (identifiers) linking them myself as I'm letting Core Data do this? </li>
  </ul>
  
  <p>Preference is SWIFT (however if someone knows in Objective-C that might help me too).  So what I'm trying to do again is:</p>
  
  <ul>
  <li>Get all PERSON objects, for which first name = "xxx", and for which they are associated with the following SCHOOL managed object.  </li>
  </ul>