iOS递归校验数据验证,去除坑爹的<null>

后台不知道是哪个坑货写的,接口经常有应该返回空串@""的, 非要返回@"<null>", 写了个方法,纠正数据
递归验证AFN请求的返回数据responseObject

+ (id)getRightData:(id)responseObject {
    if ([responseObject isKindOfClass:[NSDictionary class]]) {
        responseObject = [NSMutableDictionary dictionaryWithDictionary:responseObject];
        for (NSString *key in [responseObject allKeys]) {
           responseObject[key] = [self getRightData:responseObject[key]];
        }
    } else if ([responseObject isKindOfClass:[NSArray class]]) {
        responseObject = [NSMutableArray arrayWithArray:responseObject];
        for (NSInteger index = 0; index < [responseObject count]; index++) {
            responseObject[index] = [self getRightData:responseObject[index]];
        }
    } else if ([responseObject isKindOfClass:[NSString class]]) {
        return [NSString verify:responseObject];
    } else if ([responseObject isKindOfClass:[NSNull class]]){
        return [NSString verify:responseObject];
    }
    return responseObject;
}