So I switched to using RestKit 0.2 and CoreData and I've been having a lot of trouble trying to get the mappings correct... I don't understand why. The JSON Response of my server is like this:

{
"meta": 
   {
   "limit": 20, 
   "next": null, 
   "offset": 0, 
   "previous": null, 
   "total_count": 2
   }, 
   "objects": 
   [{
       "creation_date": "2012-10-15T20:16:47", 
       "description": "", 
       "id": 1, 
       "last_modified": 
       "2012-10-15T20:16:47", 
       "order": 1, 
       "other_names": "", 
       "primary_name": "Mixing",
       "production_line": "/api/rest/productionlines/1/", 
       "resource_uri": "/api/rest/cells/1/"
   }, 
   {
       "creation_date": "2012-10-15T20:16:47", 
       "description": "",
       "id": 2, 
       "last_modified": "2012-10-15T20:16:47",
       "order": 2, "other_names": "", 
       "primary_name": "Packaging", 
       "production_line": "/api/rest/productionlines/1/",
       "resource_uri": "/api/rest/cells/2/"
   }]
}

Then in XCode I have:

RKObjectManager *objectManager = [RKObjectManager sharedManager];

[AFNetworkActivityIndicatorManager sharedManager].enabled = YES;

NSManagedObjectModel *managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
RKManagedObjectStore *managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];
objectManager.managedObjectStore = managedObjectStore;


RKEntityMapping *cellMapping = [RKEntityMapping mappingForEntityForName:@"Cell" inManagedObjectStore:managedObjectStore];
cellMapping.primaryKeyAttribute = @"identifier";
[cellMapping addAttributeMappingsFromDictionary:@{
 @"id": @"identifier",
 @"primary_name": @"primaryName",
 }];



RKResponseDescriptor *responseCell = [RKResponseDescriptor responseDescriptorWithMapping:cellMapping
                                                                             pathPattern:@"/api/rest/cells/?format=json"
                                                                                 keyPath:@"objects"
                                                                             statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];


[objectManager addResponseDescriptorsFromArray:@[responseCell, responseUser, responseCompany]];


[managedObjectStore createPersistentStoreCoordinator];
NSString *storePath = [RKApplicationDataDirectory() stringByAppendingPathComponent:@"AppDB.sqlite"];
NSString *seedPath = [[NSBundle mainBundle] pathForResource:@"SeedDatabase" ofType:@"sqlite"];
NSError *error;
NSPersistentStore *persistentStore = [managedObjectStore addSQLitePersistentStoreAtPath:storePath fromSeedDatabaseAtPath:seedPath withConfiguration:nil options:nil error:&error];
NSAssert(persistentStore, @"Failed to add persistent store with error: %@", error);

// Create the managed object contexts
[managedObjectStore createManagedObjectContexts];

// Configure a managed object cache to ensure we do not create duplicate objects
managedObjectStore.managedObjectCache = [[RKInMemoryManagedObjectCache alloc] initWithManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];

My request is:

    [[RKObjectManager sharedManager] getObjectsAtPath:@"/api/rest/cells/?format=json" parameters:nil success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
        RKLogInfo(@"Load complete: Table should refresh...");

        [[NSUserDefaults standardUserDefaults] setObject:[NSDate date] forKey:@"LastUpdatedAt"];
        [[NSUserDefaults standardUserDefaults] synchronize];
    } failure:^(RKObjectRequestOperation *operation, NSError *error) {
        RKLogError(@"Load failed with error: %@", error);
    }];

And I always get the following error:

**Error Domain=org.restkit.RestKit.ErrorDomain Code=1001 "Unable to find any mappings for the given content" UserInfo=0x1102d500 {DetailedErrors=(), NSLocalizedDescription=Unable to find any mappings for the given content, keyPath=null}**

Thanks a lot!