将服务器获取的<null>转为""

//将从服务器获取到的<null>转掉字典套数组, 如果还有层,继续往里套 这样是不是很耗内存?

+(NSMutableDictionary *)setDictionary:(NSDictionary *)keyedValues

{

    NSMutableDictionary *dic = [[NSMutableDictionaryalloc] initWithDictionary:keyedValues];

    NSArray *valueArray= [dic allKeys];

    for (NSString *keyin valueArray) {

        if ([[dic objectForKey:key]isEqual:[NSNullnull]]) {

            [dic setObject:@""forKey:key];

        }

        if ([[dicobjectForKey:key]isKindOfClass:[NSArrayclass]]) {

            NSMutableArray *secondA = [NSMutableArrayarrayWithArray:[dic objectForKey:key]];

            NSMutableArray *SRA = [NSMutableArrayarray];

            for (NSDictionary *secondDicin secondA ) {

                NSMutableDictionary *SD = [[NSMutableDictionaryalloc] initWithDictionary:secondDic];

                NSArray *valueArray= [SD allKeys];

                for (NSString *Skeyin valueArray) {

                    if ([[SD objectForKey:Skey]isEqual:[NSNullnull]]) {

                        [SD setObject:@""forKey:Skey];

                    }

                }

                [SRA addObject:SD];

            }

            [dic setObject:SRA forKey:key];

        }

    }

    return dic;

}