• • 对于此请求：**

Alamofire.request("https://google.com").responseCollection { (response: DataResponse<[User]>) in
  guard response.result.isSuccess else {
    print(response.error)

    return
  }
}

• • 我在控制台中看到以下内容：**

可选（我的应用程序名称.后端错误. jsonSerialization（Alamofire. AFError.响应序列化失败（Alamofire. AFError.响应序列化失败原因. jsonSerializationFailureReason. jsonSerialization失败（错误域= NSCocoaErrorDomain代码= 3840 "字符0周围的值无效。"用户信息= {NSDebugDescription =字符0周围的值无效。}）））

• • 我所尝试的**

Alamofire.request("https://google.com").responseCollection { (response: DataResponse<[User]>) in
  guard response.result.isSuccess else {
    print(response.error)

    if let error1 = response.error as? AFError {
      print(error1)  // Execution DOES NOT reach here.
    }

    if let error2 = response.error as? BackendError {
      print(error2) // Execution DOES reach here.
    }

    return
  }
}

print(error2)以上图纸：
jsonSerialization（Alamofire. AF错误.响应序列化失败（Alamofire. AF错误.响应序列化失败原因. jsonSerialization失败（错误域= NSCocoaErrorDomain代码= 3840 "字符0周围的值无效。"用户信息= {NSDebugDescription =字符0周围的值无效。}））

• • 我尝试做的是找到底层错误，以便解析domain、code和userInfo属性。**

我创建了BackendError枚举，Alamofire在www.example.com上提供了这个枚举作为示例：https://github.com/Alamofire/Alamofire#handling-errors :

enum BackendError: Error {
    case network(error: Error) // Capture any underlying Error from the URLSession API
    case dataSerialization(error: Error)
    case jsonSerialization(error: Error)
    case xmlSerialization(error: Error)
    case objectSerialization(reason: String)
}

并且我还实现了与www.example.com上的示例完全相同的示例通用响应对象序列化：https://github.com/Alamofire/Alamofire#generic-response-object-serialization :

extension DataRequest {
  @discardableResult
  func responseCollection<T: ResponseCollectionSerializable>(
    queue: DispatchQueue? = nil,
    completionHandler: @escaping (DataResponse<[T]>) -> Void) -> Self {
    let responseSerializer = DataResponseSerializer<[T]> { request, response, data, error in
      guard error == nil else {
        return .failure(BackendError.network(error: error!))
      }

      let jsonSerializer = DataRequest.jsonResponseSerializer(options: .allowFragments)
      let result = jsonSerializer.serializeResponse(request, response, data, nil)

      guard case let .success(jsonObject) = result else {
        return .failure(BackendError.jsonSerialization(error: result.error!))
      }

      guard let response = response else {
        let reason = "Response collection could not be serialized due to nil response."
        return .failure(BackendError.objectSerialization(reason: reason))
      }

      return .success(T.collection(from: response, withRepresentation: jsonObject))
    }

    return response(responseSerializer: responseSerializer, completionHandler: completionHandler)
  }
}

我认为有switch es，case s，以及BackendError，AFError，Error和/或NSError之间的转换，但我似乎不能得到它。

• • 如何找到底层错误，以便解析domain、code和userInfo属性？**

我用的是Swift 3和Alamofire 4.3.0。