title: NSBatchUpdateRequest for one-to-many relationship
body: <p>I am trying to use NSBatchUpdateRequest to update a one-to-many relationship. </p>
  
  <p>My entity, Presentation, has multiple Slide, which is another entity, and they have an inverse relationship.</p>
  
  <p><a href="https://i.stack.imgur.com/kDGLO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/kDGLO.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/UdJkV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UdJkV.png" alt="enter image description here"></a></p>
  
  <p>When I try to update slides, I get this error:</p>
  
  <p>*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Invalid relationship ((), name slides, isOptional 1, isTransient 0, entity Presentation, renamingIdentifier slides, validation predicates (
  ), warnings (
  ), versionHashModifier (null)
   userInfo {
  }, destination entity Slide, inverseRelationship presentation, minCount 0, maxCount 0, isOrdered 0, deleteRule 1) passed to propertiesToUpdate:'</p>
  
  <p>I've tried to search for this error, but couldn't find any results.</p>
  
  <p>My code:</p>
  
  <pre><code>let entity = NSEntityDescription.entityForName("Presentation", inManagedObjectContext: managedObjectContext)
  let batchRequest = NSBatchUpdateRequest(entity: entity!)
  batchRequest.resultType = .UpdatedObjectIDsResultType
  batchRequest.propertiesToUpdate = ["date_updated": formattedDateUpdated, "slides": presentationSlides]
  
  do {
        let batchUpdateResult = try managedObjectContext.executeRequest(batchRequest) as! NSBatchUpdateResult
        let objectIds = batchUpdateResult.result as! [NSManagedObjectID]
  
        for objectId in objectIds {
            let managedObject = managedObjectContext.objectWithID(objectId)
  
            managedObjectContext.refreshObject(managedObject, mergeChanges: false)
        }
   } catch {
            let updateError = error as NSError
            print(updateError)
   }
  </code></pre>
  
  <p>date_updated updated just fine, so I don't think this is the correct way of updating a relationship.</p>
  
  <p>If anyone needs more code, please let me know. Thanks for any help.</p>