json - 在 Swift 中将可选元素附加到 json 数组中

Question

我刚刚开始熟悉 JSON。我有一个类对象，我通过传入 JSON 来初始化它。该对象有一个可能为空的数组，我需要检查它的值。到目前为止我正在尝试:

    init(json: JSON) {
    id = json["id"].string
    type = json["type"].string
    text = json["text"].string
    answer = json["answer"].string
    format = json["format"].string
    answeredBy = []

    if let answeredByjson = json["answeredBy"].array {
        for (_, userDict) in answeredByjson {
           if let userDict = userDict as? [String : Any] {
                answeredBy.append(JSON(User(dictionary: userDict)))
            }
        }
    }
}

数组中的元素是必须用于初始化另一个对象(用户)的字典。我收到的错误是:

Expression type '[JSON]' is ambiguous without more context.

如何更新我的代码？

这是我的 json:

    {        
    "answer" : "rachel",
      "answeredBy" : {
       "j1K4WXbOFRXfm3srk9oMtZJ8Iop2" : {
          "email" : "an email",
          "pictureURL" : "a URL",
          "uid" : "j1K4WXbOFRXfm3srk9oMtZJ8Iop2",
          "name" : "a name"
        },
        "vtYlmyerugedizHyOW6TV847Be23" : {
          "email" : "an email",
          "pictureURL" : "a URL",
          "uid" : "vtYlmyerugedizHyOW6TV847Be23",
          "name" : "Rusty Shakleford"
        }
      },
      "format" : "field",
      "id" : "1",
      "type" : "text",
      "text" : "In a foot race, Jerry was neither first nor last. Janet beat Jerry, Jerry beat Pat. Charlie was neither first nor last. Charlie beat Rachel. Pat beat Charlie. Who came in last?"
    }

Answer 1

if let answeredByjson = json["answeredBy"].array {
    ...
}

生成一个数组[JSON]，但您希望它生成一个字典[String: JSON]。这就是为什么您会收到:

Expression type '[JSON]' is ambiguous without more context

生成字典:

if let answeredByjson = json["answeredBy"].dictionary {
    ...
}

如果您不希望它生成字典[String: JSON]，那么这一行就没有意义

for (_, userDict) in answeredByjson {