title: Core Data Crashing during NSManagedObjectContext processPendingChanges
body: <p>I am getting a (what seems to me as a strange) crash with Core Data.
  From what I can gather it is happening when Core Data does a save and subsequent managedObjectContextDidSave methods are fired.</p>
  
  <p>I am at a loss and really hoping someone can help me out or guide me in the right direction.</p>
  
  <p>The crash report is as follows:</p>
  
  <pre><code>Exception Type:  EXC_BAD_ACCESS (SIGBUS)
  Exception Codes: KERN_PROTECTION_FAILURE at 0x0000000b
  Crashed Thread:  0
  
  Thread 0 Crashed:
  0   libobjc.A.dylib                 0x000026f4 objc_msgSend + 16
  1   Foundation                      0x000437a4 NSClassFromObject + 8
  2   Foundation                      0x0000ba54 _NSIMPForObjectAndSelector + 4
  3   Foundation                      0x00095eae -[NSSortDescriptor compareObject:toObject:] + 110
  4   CoreData                        0x000b0a6e +[NSFetchedResultsController(PrivateMethods) _insertIndexForObject:inArray:lowIdx:highIdx:sortDescriptors:] + 174
  5   CoreData                        0x000b1496 -[NSFetchedResultsController(PrivateMethods) _postprocessInsertedObjects:] + 342
  6   CoreData                        0x000b32d6 -[NSFetchedResultsController(PrivateMethods) _postprocessUpdatedObjects:] + 430
  7   CoreData                        0x000b2a5e -[NSFetchedResultsController(PrivateMethods) _managedObjectContextDidChange:] + 498
  8   Foundation                      0x0004bbf6 _nsnote_callback + 162
  9   CoreFoundation                  0x00050af2 _CFXNotificationPostNotification + 298
  10  Foundation                      0x000497f4 -[NSNotificationCenter postNotificationName:object:userInfo:] + 64
  11  CoreData                        0x0002e42e -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:] + 66
  12  CoreData                        0x0007fd26 -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:withDeletions:withUpdates:withRefreshes:] + 134
  13  CoreData                        0x0001670a -[NSManagedObjectContext(_NSInternalChangeProcessing) _postRefreshedObjectsNotificationAndClearList] + 70
  14  CoreData                        0x000164ac -[NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:] + 1656
  15  CoreData                        0x0004b5fa -[NSManagedObjectContext processPendingChanges] + 10
  16  CoreData                        0x0003e2a4 _performRunLoopAction + 120
  17  CoreFoundation                  0x0000fb50 __CFRunLoopDoObservers + 420
  18  CoreFoundation                  0x00056a32 CFRunLoopRunSpecific + 1734
  19  CoreFoundation                  0x00056356 CFRunLoopRunInMode + 42
  20  GraphicsServices                0x00003cb8 GSEventRunModal + 108
  21  GraphicsServices                0x00003d64 GSEventRun + 56
  22  UIKit                           0x00002768 -[UIApplication _run] + 384
  23  UIKit                           0x0000146c UIApplicationMain + 688
  24  MyApp                           0x000022d2 main (main.m:14)
  25  MyApp                           0x00002248 start + 44
  </code></pre>