Backtrace

Thread 24, Queue : NSManagedObjectContext Queue
#0  0x39f26944 in objc_exception_throw ()
#1	0x3223529c in +[NSException raise:format:arguments:] ()
#2	0x32b0bffe in -[NSAssertionHandler handleFailureInFunction:file:lineNumber:description:] ()
#3	0x0032d5e4 in RKEntityIdentificationAttributesForEntityMappingWithRepresentation at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/CoreData/RKManagedObjectMappingOperationDataSource.m:83
#4	0x0032c79a in -[RKManagedObjectMappingOperationDataSource mappingOperation:targetObjectForRepresentation:withMapping:inRelationship:] at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/CoreData/RKManagedObjectMappingOperationDataSource.m:239
#5	0x000d657c in -[UTManagedObjectMappingOperationDataSource mappingOperation:targetObjectForRepresentation:withMapping:inRelationship:] at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/UTFramework/UTAPI/UTManagedObjectMappingOperationDataSource.m:23
#6	0x0033fb52 in -[RKMapperOperation objectForRepresentation:withMapping:] at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:297
#7	0x0033e3e6 in __63-[RKMapperOperation mapRepresentations:atKeyPath:usingMapping:]_block_invoke at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:221
#8	0x32229aea in __NSArrayEnumerate ()
#9	0x3218be36 in -[NSArray enumerateObjectsWithOptions:usingBlock:] ()
#10	0x0033e2de in -[RKMapperOperation mapRepresentations:atKeyPath:usingMapping:] at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:220
#11	0x0033fdca in -[RKMapperOperation mapRepresentationOrRepresentations:atKeyPath:usingMapping:] at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:308
#12	0x00340658 in -[RKMapperOperation mapSourceRepresentationWithMappingsDictionary:] at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:355
#13	0x00340f72 in -[RKMapperOperation main] at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/ObjectMapping/RKMapperOperation.m:393
#14	0x32ac3a88 in -[__NSOperationInternal start] ()
#15	0x00308d2a in __73-[RKManagedObjectResponseMapperOperation performMappingWithObject:error:]_block_invoke at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/Network/RKResponseMapperOperation.m:406
#16	0x32031db8 in developerSubmittedBlockToNSManagedObjectContextPerform ()
#17	0x3a3405da in _dispatch_client_callout ()
#18	0x3a34380e in _dispatch_barrier_sync_f_invoke ()
#19	0x32031f3a in -[NSManagedObjectContext performBlockAndWait:] ()
#20	0x00307abe in -[RKManagedObjectResponseMapperOperation performMappingWithObject:error:] at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/Network/RKResponseMapperOperation.m:363
#21	0x00305cfa in -[RKResponseMapperOperation main] at /Users/Mat/Dropbox/Code/iPhone/UpTo-iOS/Pods/RestKit/Code/Network/RKResponseMapperOperation.m:284
#22	0x32ac3a88 in -[__NSOperationInternal start] ()
#23	0x32b3bfe6 in __block_global_6 ()
#24	0x3a340792 in _dispatch_call_block_and_release ()
#25	0x3a344656 in _dispatch_root_queue_drain ()
#26	0x3a3447d8 in _dispatch_worker_thread2 ()
#27	0x3a3687f0 in _pthread_wqthread ()

Sample JSON

   {
      "User":{
         "id":"80356",
         "username":"",
         "password":"",
         "fb_username":null,
         "fb_permissions":null,
         "twt_id":null,
         "twt_username":null,
         "twt_oauth":null,
         "twt_oauth_secret":null,
         "active":"1",
         "admin":"0",
         "banned":"0",
         "reset_key":null,
         "reset_expires":"2013-01-08 15:08:08",
         "deleted":"0",
         "created":"2012-12-18 03:18:31",
         "modified":"2012-12-18 03:18:31",
         "type":"user",
         "nudged":"2013-01-01 07:46:58",
         "noFriendNudged":null,
         "version_id":"6",
         "default_category_id":null,
         "status":0,
         "Profile":{
            "id":"79905",
            "user_id":"80356",
            "birthday":"1979-03-06",
            "bio":"",
            "cover_photo":null
         }
      }
   },
   {
      "Contact":{
         "name":"K",
         "network_name":"facebook",
         "network_id":"",
         "photo":"",
         "weight":"2"
      }
   }