如何从Alamofire错误中找出潜在的错误？ [英] How do I get at the underlying Error from an Alamofire error?

问题描述

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（my_app_name.BackendError.jsonSerialization（Alamofire.AFError.responseSerializationFailed（Alamofire.AFError.ResponseSerializationFailureReason.jsonSerializationFailed（错误
Domain = NSCocoaErrorDomain代码= 3840字符
0周围的无效值。 UserInfo = {NSDebugDescription =字符0周围的无效值。}））））））

Optional(my_app_name.BackendError.jsonSerialization(Alamofire.AFError.responseSerializationFailed(Alamofire.AFError.ResponseSerializationFailureReason.jsonSerializationFailed(Error Domain=NSCocoaErrorDomain Code=3840 "Invalid value around character 0." UserInfo={NSDebugDescription=Invalid value around character 0.}))))

我尝试过的操作：

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）以上打印内容：

jsonSerialization（Alamofire.AFError .responseSerializationFailed（Alamofire.AFError.ResponseSerializationFailureReason.jsonSerializationFailed（错误
域= NSCocoaErrorDomain代码= 3840字符
0周围的无效值。 UserInfo = {NSDebugDescription =字符0周围的无效值。））））

jsonSerialization(Alamofire.AFError.responseSerializationFailed(Alamofire.AFError.ResponseSerializationFailureReason.jsonSerializationFailed(Error Domain=NSCocoaErrorDomain Code=3840 "Invalid value around character 0." UserInfo={NSDebugDescription=Invalid value around character 0.})))

我要尝试的是获取基本错误，以便我可以解析域，代码和 userInfo 属性。

What I'm trying to do is get at the underlying error so I can parse the domain, code, and userInfo properties.

我创建了 BackendError 枚举，该枚举由Alamofire提供，例如，在 https://github.com/Alamofire/Alamofire#handling-errors ：

I created the BackendError enum that Alamofire provides as an example at 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)
}

并且我还实现了示例通用响应对象序列化与 https://github.com/Alamofire/Alamofire ＃generic-response-object-serialization ：

and I also implemented the example generic response object serialization exactly like the example at 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)
  }
}

我认为有个开关 es， case s，并强制转换为和来自 BackendError ， AFError ， Error 和/或 NSError ，但我似乎无法理解。

I think there are switches, cases, and casts to and from BackendError, AFError, Error, and/or NSError, but I can't seem to get it.

如何获取基本错误这样我就可以解析域，代码和 userInfo 属性？

How can I get at the underlying error so I can parse the domain, code, and userInfo properties?

我正在使用Swift 3和Alamofire 4.3.0。

I'm using Swift 3 and Alamofire 4.3.0 .

推荐答案

查看 response.result ：

if case let .failure(error) = response.result {
    let error = error as NSError
    print("\(error.domain)")
    print("\(error.code)")
    print("\(error.userInfo)")
}

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