gistfile1.m

+ (NSManagedObject *)managedObjectFromStructure:(NSDictionary *)structureDictionary 
                                     entityName:(NSString *)entityName 
                       withManagedObjectContext:(NSManagedObjectContext *)context {
    
    NSMutableDictionary *mutableStructureDictionary = [structureDictionary mutableCopy];

    NSManagedObject *managedObject = nil;
    NSManagedObjectModel *model = [context.persistentStoreCoordinator managedObjectModel];
    
    for (NSString *property in [mutableStructureDictionary allKeys]) {
        NSString *fetchRequestName = [NSString stringWithFormat:@"%@_%@", entityName, property];
        if ([model fetchRequestTemplateForName:fetchRequestName]) {
            NSDictionary *fetchDictionary = [NSDictionary dictionaryWithObject:[mutableStructureDictionary objectForKey:property] forKey:property];
            NSFetchRequest *fetchRequest = [model fetchRequestFromTemplateWithName:fetchRequestName substitutionVariables:fetchDictionary];
            NSArray *results = [context executeFetchRequest:fetchRequest error:NULL];
            if ([results count]) {
                managedObject = [results objectAtIndex:0];
            }
        }
    }
    
    if (!managedObject) {
        managedObject = [NSEntityDescription insertNewObjectForEntityForName:entityName 
                                                      inManagedObjectContext:context];
    }
    
    NSDictionary *relationshipsByName = [[managedObject entity] relationshipsByName];
    
    for (NSString *relationshipName in [relationshipsByName allKeys]) {
        NSRelationshipDescription *relationshipDescription = [relationshipsByName objectForKey:relationshipName];
        NSString *relationshipEntityName = [[relationshipDescription destinationEntity] name];
        
        if (![relationshipDescription isToMany]) {
            NSDictionary *childStructureDictionary = [mutableStructureDictionary objectForKey:relationshipName];
            NSManagedObject *childObject = [[self class] managedObjectFromStructure:childStructureDictionary 
                                                                         entityName:relationshipEntityName 
                                                           withManagedObjectContext:context];
            [managedObject setValue:childObject forKey:relationshipName];
        } else {
            NSMutableSet *relationshipSet = [managedObject mutableSetValueForKey:relationshipName];
            NSArray *relationshipArray = [mutableStructureDictionary objectForKey:relationshipName];
            
            for (NSDictionary *childStructureDictionary in relationshipArray) {
                NSManagedObject *childObject = [[self class] managedObjectFromStructure:childStructureDictionary 
                                                                             entityName:relationshipEntityName 
                                                               withManagedObjectContext:context];
                [relationshipSet addObject:childObject];
            }
        }
        
        [mutableStructureDictionary removeObjectForKey:relationshipName];
    }
    
    [managedObject setValuesForKeysWithDictionary:mutableStructureDictionary];
    
    [mutableStructureDictionary release];
    
    return managedObject;
}