问有没有办法在HTTP错误期间获得响应体？

EN

Alamofire.request(mutableURLRequest).validate().responseJSON() {
    (response) in
    switch response.result {
        case .Success(let data):
            if let jsonResult = data as? NSDictionary {
                completion(jsonResult, error: nil)
            } else if let jsonArray = data as? NSArray {
                let jsonResult = ["array" : jsonArray]
                completion(jsonResult, error: nil)
            }
        case .Failure(let error):
            //error tells me 403
            //response.result.data can't be cast to NSDictionary or NSArray like
            //the successful cases, how do I get the response body?
    }