gistfile1.txt

+ (id)fetchFirst:(BOOL)first managedObjectWithPredicateFormat:(NSString *)format, ... {
    va_list args;
    va_start(args, format);
    return [self fetchFirst:first managedObjectWithPrefetchedKeyPaths:nil predicateFormat:format arguments:args];
    va_end(args);
}

+ (id)fetchFirst:(BOOL)first managedObjectWithPrefetchedKeyPaths:(NSArray *)prefetched predicateFormat:(NSString *)format, ... { 
    va_list args;
    va_start(args, format);
    return [self fetchFirst:first managedObjectWithPrefetchedKeyPaths:prefetched predicateFormat:format arguments:args];
    va_end(args);
}

+ (id)fetchFirst:(BOOL)first managedObjectWithPrefetchedKeyPaths:(NSArray *)prefetched predicateFormat:(NSString *)format arguments:(va_list)args {
    NSManagedObjectContext *context = [NSManagedObjectContext IY_threadSpecificContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    
    NSString *entityName = NSStringFromClass([self class]);
    NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:context];
    [fetchRequest setEntity:entity];
    
    if (prefetched) {
        [fetchRequest setRelationshipKeyPathsForPrefetching:prefetched];
    }
    
    if (format) {
        NSPredicate *predicate = [NSPredicate predicateWithFormat:format arguments:args];
        [fetchRequest setPredicate:predicate];
    }   
    
    NSError *error = nil;
    NSArray *array = [context executeFetchRequest:fetchRequest error:&error];
    [fetchRequest release];
    if (error) {
        NSLog(@"%@", [error localizedDescription]);
    }
    
    if (first)
    {
        if ([array count] > 0) {
            return [array objectAtIndex:0];
        } else {
            return nil;
        }
    } else {
        return array;
    }
}