AFNetworking + FastEasyMapping не маппит объекты из JSON

[olegmelnik]

Пишу на русском заведомо зная, что компания Украинская. Надеюсь на очень быструю помощь)
C сервера приходит следующий json:

{
    "auto_load_more_enabled" = 1;
    "is_direct_v2_enabled" = 1;
    items =     (
                {
            caption =             {
                "bit_flags" = 0;
                "content_type" = comment;
                "created_at" = 1443217230;
                "created_at_utc" = 1443246030;
                "media_id" = 1082094397765659443;
                pk = 1082107015322609678;
                status = Active;
                text = "text";
                type = 1;
                user =                 {
                    "full_name" = "name";
                    "is_private" = 0;
                    pk = 123213213;
                    "profile_pic_url" = "<url>";
                    username = julianafed;
                };
                "user_id" = 197974297;
            };
            "caption_is_edited" = 1;
            code = 8EXx8gQysz;
            "comment_count" = 1;
            comments =             (
            );
            "device_timestamp" = 1443215597;
            "has_liked" = 0;
            "has_more_comments" = 0;
            id = "1082094397765659443_197974297";
            "image_versions2" =             {
                candidates =                 (
                                        {
                        height = 1080;
                        url = "<url>";
                        width = 1080;
                    },
                                        {
                        height = 750;
                        url = "<url>";
                        width = 750;
                    }
                );
            };
            "like_count" = 19;
            "media_type" = 1;
            "original_height" = 1080;
            "original_width" = 1080;
            "photo_of_you" = 0;
            pk = 1082094397765659443;
            "taken_at" = 1443215726;
            user =             {
                "full_name" = "name";
                "has_anonymous_profile_picture" = 0;
                "is_private" = 0;
                "is_unpublished" = 0;
                pk = 197974297;
                "profile_pic_url" = "<url>";
                username = julianafed;
            };
        },
    ....
  )
}

Сам запрос и передача NSDictionary на маппинг:

- (void)getTimelineFeedWithSuccess:(void(^)(AFHTTPRequestOperation *operation, NSArray *mappingResult))success
                           failure:(void(^)(AFHTTPRequestOperation *operation, NSError *error))failure
{
    [_requestOperationManager GET:@"/api/v1/feed/timeline/"
                       parameters:nil
                          success:^(AFHTTPRequestOperation *operation, NSDictionary *responseObject) {
                              FEMMapping *mapping = [Media defaultMapping];
                              NSArray *mappingResult = [FEMDeserializer collectionFromRepresentation:[responseObject objectForKey:@"items"]
                                                                                             mapping:mapping
                                                                                             context:SharedAppDelegate.managedObjectContext];

                              success(operation, mappingResult);
                          } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                              failure(operation, error);
                          }];
}

Сгенерированная CoreData`ой .h файл модели:

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@class Comment, User;

@interface Media : NSManagedObject

@property (nonatomic, getter=isCaptionEdited) BOOL captionEdited;
@property (nonatomic, retain) NSString *clientCacheKey;
@property (nonatomic, retain) NSString *code;
@property (nonatomic, retain) NSNumber *commentsCount;
@property (nonatomic, retain) NSNumber *deviceTimestamp;
@property (nonatomic, retain) NSNumber *filterType;
@property (nonatomic, retain) NSNumber *audioEnable;
@property (nonatomic, getter=isLiked) BOOL liked;
@property (nonatomic, retain) NSNumber *moreComments;
@property (nonatomic, retain) NSNumber *mediaID;
@property (nonatomic, retain) NSNumber *likesCount;
@property (nonatomic, retain) NSNumber *mediaType;
@property (nonatomic, retain) NSNumber *originalHeight;
@property (nonatomic, retain) NSNumber *originalWidth;
@property (nonatomic, getter=isUserPhoto) BOOL userPhoto;
@property (nonatomic, retain) NSNumber *pk;
@property (nonatomic, retain) NSNumber *takenAt;
@property (nonatomic, retain) NSOrderedSet *videoVersion;
@property (nonatomic, retain) NSOrderedSet *imageVersion;
@property (nonatomic, retain) User *user;
@property (nonatomic, retain) Comment *caption;
@property (nonatomic, retain) NSOrderedSet *comments;

@end

@interface Media (CoreDataGeneratedAccessors)

+ (FEMMapping *)defaultMapping;

- (void)insertObject:(NSManagedObject *)value inVideoVersionAtIndex:(NSUInteger)idx;
- (void)removeObjectFromVideoVersionAtIndex:(NSUInteger)idx;
- (void)insertVideoVersion:(NSArray<NSManagedObject *> *)value atIndexes:(NSIndexSet *)indexes;
- (void)removeVideoVersionAtIndexes:(NSIndexSet *)indexes;
- (void)replaceObjectInVideoVersionAtIndex:(NSUInteger)idx withObject:(NSManagedObject *)value;
- (void)replaceVideoVersionAtIndexes:(NSIndexSet *)indexes withVideoVersion:(NSArray<NSManagedObject *> *)values;
- (void)addVideoVersionObject:(NSManagedObject *)value;
- (void)removeVideoVersionObject:(NSManagedObject *)value;
- (void)addVideoVersion:(NSOrderedSet<NSManagedObject *> *)values;
- (void)removeVideoVersion:(NSOrderedSet<NSManagedObject *> *)values;

- (void)insertObject:(NSManagedObject *)value inImageVersionAtIndex:(NSUInteger)idx;
- (void)removeObjectFromImageVersionAtIndex:(NSUInteger)idx;
- (void)insertImageVersion:(NSArray<NSManagedObject *> *)value atIndexes:(NSIndexSet *)indexes;
- (void)removeImageVersionAtIndexes:(NSIndexSet *)indexes;
- (void)replaceObjectInImageVersionAtIndex:(NSUInteger)idx withObject:(NSManagedObject *)value;
- (void)replaceImageVersionAtIndexes:(NSIndexSet *)indexes withImageVersion:(NSArray<NSManagedObject *> *)values;
- (void)addImageVersionObject:(NSManagedObject *)value;
- (void)removeImageVersionObject:(NSManagedObject *)value;
- (void)addImageVersion:(NSOrderedSet<NSManagedObject *> *)values;
- (void)removeImageVersion:(NSOrderedSet<NSManagedObject *> *)values;

- (void)insertObject:(NSManagedObject *)value inCommentsAtIndex:(NSUInteger)idx;
- (void)removeObjectFromCommentsAtIndex:(NSUInteger)idx;
- (void)insertComments:(NSArray<NSManagedObject *> *)value atIndexes:(NSIndexSet *)indexes;
- (void)removeCommentsAtIndexes:(NSIndexSet *)indexes;
- (void)replaceObjectInCommentsAtIndex:(NSUInteger)idx withObject:(NSManagedObject *)value;
- (void)replaceCommentsAtIndexes:(NSIndexSet *)indexes withComments:(NSArray<NSManagedObject *> *)values;
- (void)addCommentsObject:(NSManagedObject *)value;
- (void)removeCommentsObject:(NSManagedObject *)value;
- (void)addComments:(NSOrderedSet<NSManagedObject *> *)values;
- (void)removeComments:(NSOrderedSet<NSManagedObject *> *)values;

@end

Имплиментация модели с маппингом:

#import "Media.h"
#import "Comment.h"
#import "User.h"
#import "VideoVersion.h"

@implementation Media

@dynamic captionEdited;
@dynamic clientCacheKey;
@dynamic code;
@dynamic commentsCount;
@dynamic deviceTimestamp;
@dynamic filterType;
@dynamic audioEnable;
@dynamic liked;
@dynamic moreComments;
@dynamic mediaID;
@dynamic likesCount;
@dynamic mediaType;
@dynamic originalHeight;
@dynamic originalWidth;
@dynamic userPhoto;
@dynamic pk;
@dynamic takenAt;
@dynamic videoVersion;
@dynamic imageVersion;
@dynamic user;
@dynamic caption;
@dynamic comments;

- (BOOL)isLiked
{
    [self willAccessValueForKey:@"liked"];
    BOOL liked = [self primitiveValueForKey:@"liked"];
    [self didAccessValueForKey:@"liked"];

    return liked;
}

- (BOOL)isUserPhoto
{
    [self willAccessValueForKey:@"userPhoto"];
    BOOL userPhoto = [self primitiveValueForKey:@"userPhoto"];
    [self didAccessValueForKey:@"userPhoto"];

    return userPhoto;
}

- (BOOL)isCaptionEdited
{
    [self willAccessValueForKey:@"captionEdited"];
    BOOL captionEdited = [self primitiveValueForKey:@"captionEdited"];
    [self didAccessValueForKey:@"captionEdited"];
    return captionEdited;
}

+ (NSDictionary *)elementToPropertyMappings {
    return @{
             @"caption_is_edited" : @"captionEdited",
             @"client_cache_key" : @"clientCacheKey",
             @"code" : @"code",
             @"comment_count" : @"commentsCount",
             @"device_timestamp" : @"deviceTimestamp",
             @"filter_type" : @"filterType",
             @"has_audio" : @"audioEnable",
             @"has_liked" : @"liked",
             @"has_more_comments" : @"moreComments",
             @"like_count" : @"mediaID",
             @"original_height" : @"originalHeight",
             @"original_width" : @"originalWidth",
             @"photo_of_you" : @"userPhoto",
             @"pk" : @"pk",
             @"taken_at" : @"takenAt",
             };
}

+ (FEMMapping *)defaultMapping {
    FEMMapping *mapping = [[FEMMapping alloc] initWithEntityName:@"Media"];
    [mapping addAttributesFromDictionary:[Media elementToPropertyMappings]];
    [mapping addRelationshipMapping:[Comment defaultMapping] forProperty:@"caption" keyPath:@"caption"];
    [mapping addRelationshipMapping:[User defaultMapping] forProperty:@"user" keyPath:@"user"];
    [mapping addToManyRelationshipMapping:[VideoVersion defaultMapping] forProperty:@"videoVersion" keyPath:@"video_versions"];
    [mapping addToManyRelationshipMapping:[Comment defaultMapping] forProperty:@"comments" keyPath:@"comments"];
    return mapping;
}

@end

По факту все работает и ниодной ошибки в логе нет, но при выводе объекта в лог получается:

<Media: 0x7fd509de9640> (entity: Media; id: 0x7fd509d4feb0 <x-coredata:///Media/tF63F01BE-D0D8-4978-8BDE-913E888F1B7F2> ; data: {
    audioEnable = nil;
    caption = "0x7fd50c4ce4d0 <x-coredata:///Comment/tF63F01BE-D0D8-4978-8BDE-913E888F1B7F3>";
    captionEdited = 0;
    clientCacheKey = nil;
    code = 8EXx8gQysz;
    comments =     (
    );
    commentsCount = 0;
    deviceTimestamp = 0;
    filterType = 0;
    imageVersion =     (
    );
    liked = 1;
    likesCount = 0;
    mediaID = 0;
    mediaType = 0;
    moreComments = nil;
    originalHeight = 0;
    originalWidth = 0;
    pk = "-2147483648";
    takenAt = 0;
    user = "0x7fd509de9d40 <x-coredata:///User/tF63F01BE-D0D8-4978-8BDE-913E888F1B7F5>";
    userPhoto = 0;
    videoVersion =     (
    );
})

То есть некоторые объекты маппятся верно, некоторые вообще не маппятся, третьи представляют из себя отрицательные числа.
Подскажите, пожалуйста, что я делаю не так и как мне исправить? Заранее спасибо.