the way i create restkit model

gistfile1.m

//
//  Model.m
//  TNN
//
//  Created by Abdullah Bakhach on 11/20/13.
//  Copyright (c) 2013 larochesoft. All rights reserved.
//

#import <CoreData/CoreData.h>
#import "RKManagedObjectStore.h"
#import "Model.h"
#import "TNNRestClient.h"
#import "RKXMLReaderSerialization.h"

static Model *singleton = nil;

@implementation Model

+ (id)getSingleton { 
	@synchronized(self) {
		if (singleton == nil) {
			singleton = [[self alloc] init];
            [singleton setupDatabase];
        }
    }
	return singleton;
}

- (void)setupDatabase {
    NSError *error = nil;
    NSURL *modelURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"TNN" ofType:@"momd"]];
    // NOTE: Due to an iOS 5 bug, the managed object model returned is immutable.
    NSManagedObjectModel *managedObjectModel = [[[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL] mutableCopy];
    singleton.managedObjectStore = [[RKManagedObjectStore alloc] initWithManagedObjectModel:managedObjectModel];
    
    // Initialize the Core Data stack
    [singleton.managedObjectStore createPersistentStoreCoordinator];
    
    // Configure Core Data Integration
    BOOL success = RKEnsureDirectoryExistsAtPath(RKApplicationDataDirectory(), &error);
    if (! success) {
        RKLogError(@"Failed to create Application Data Directory at path '%@': %@", RKApplicationDataDirectory(), error);
    }
    
    //NSDictionary *options = @{ NSSQLitePragmasOption : @{@"journal_mode" : @"DELETE"} };

    NSString *path = [RKApplicationDataDirectory() stringByAppendingPathComponent:@"Store.sqlite"];
    
    NSPersistentStore *persistentStore = [singleton.managedObjectStore addSQLitePersistentStoreAtPath:path
                                                                      fromSeedDatabaseAtPath:nil
                                                                           withConfiguration:nil
                                                                                     options:nil
                                                                                       error:&error];
    if (! persistentStore) {
        RKLogError(@"Failed adding persistent store at path '%@': %@", path, error);
    }
    
    [singleton.managedObjectStore createManagedObjectContexts];
    
    // Set the default store shared instance
    [RKManagedObjectStore setDefaultStore:singleton.managedObjectStore];
    
    
    // Configure the object manager
    TNNRestClient *client = [TNNRestClient getSingleton];
    singleton.objectManager = [[RKObjectManager alloc] initWithHTTPClient:client];
    singleton.objectManager.managedObjectStore = singleton.managedObjectStore;
    [RKMIMETypeSerialization registerClass:[RKXMLReaderSerialization class] forMIMEType:@"text/xml"];
    [[RKObjectManager sharedManager] setAcceptHeaderWithMIMEType:RKMIMETypeTextXML];
    
    [RKObjectManager setSharedManager:singleton.objectManager];
    
    
    // configure date fomratting
    NSDateFormatter *dateFormatter = [NSDateFormatter new];
    [dateFormatter  setDateFormat:@"yyyy-MM-dd"];
    dateFormatter.timeZone = [NSTimeZone timeZoneWithAbbreviation:@"UTC"];
    dateFormatter.locale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"];
    
    [RKObjectMapping addDefaultDateFormatter:dateFormatter];
    

}

- (void)setResponseDescriptors {
    //[[Exam getSingleton] addResponseDescriptor];
    //[[Subject getSingleton] addResponseDescriptor];
    
}

@end