Swift 4 json解码器错误flickr

Question

我正在swift 4中试用新的JSONDecoder()，并试图解析以下flickr API响应:(https://API.flickr.com/services/rest/？api_key=api_key&method=flickr.photos.search&format=json&per_page=25&text=hello&nojsonCallback=1).但是，我得到一个错误，说“错误处理json数据：数据不能被读取，因为它的格式不正确。”然而，数据似乎是在正确的格式对我。我做错什么了吗？

            let dataTask = session.dataTask(with: urlRequest) { (data, response, error) in
                if let error = error {
                    print("json error: \(error.localizedDescription)")
                    return
                } else if let data = data {
                    print(response)
                    do {
                        let decoder = JSONDecoder()
                        print(data)
                        let flickrPhotos = try decoder.decode(FlickrImageResult.self, from: data)
                    } catch {
                        dump(data)
                        print("json error: \(error.localizedDescription)")
                    }
                }
            }
            dataTask.resume()

我的数据模型是

struct FlickrImageResult : Codable {
     var photos : FlickrPhoto? = nil

}

struct FlickrPhoto : Codable {
    var photo : [FlickrURLs]? = nil
 }

struct FlickrURLs: Codable {
    var id : String? = nil
    var owner: String? = nil
    var secret: String? = nil
    var server: String? = nil
    var farm: String? = nil
}

我将请求的图像数更改为2，打印出的数据返回可选（{“photos”：{“page”：1,“pages”：120197，“perpage”：2,“total”：“240393”,“photo”：[{“id”：“36729752762”，“owner”：“152440263@N02”，“secret”：“E62BA3E18B”，“server”：“4432”，“farm”：5,“title”：“Hello there”，“ispublic”：1,“isfriend”：0,“isfamily”：0}，{“id”：“36729384952”，“

Answer 1

您的模型的唯一问题是farm实际上是一个int。以下是您的模型的更完整版本，它与文档（https://www.flickr.com/services/api/flickr.photos.search.html）一致：

struct FlickrImageResult: Codable {
    let photos : FlickrPagedImageResult?
    let stat: String
}

struct FlickrPagedImageResult: Codable {
    let photo : [FlickrURLs]
    let page: Int
    let pages: Int
    let perpage: Int
    let total: String
}

struct FlickrURLs: Codable {
    let id : String
    let owner: String
    let secret: String
    let server: String
    let farm: Int
    // let title: String
    // If needed, camel-case and use CodingKeys enum
    //let ispublic: Int
    //let isfriend: Int
    //let isfamily: Int
}

let jsonData = """
{
  "photos": {
    "page": 1,
    "pages": 13651,
    "perpage": 25,
    "total": "341263",
    "photo": [
      {
        "id": "36499638920",
        "owner": "55126206@N07",
        "secret": "7e82dee0ba",
        "server": "4346",
        "farm": 5,
        "title": "[BREATHE]-Ririko,Sayaka&Chiyoko",
        "ispublic": 1,
        "isfriend": 0,
        "isfamily": 0
      },
      {
        "id": "36724435032",
        "owner": "92807782@N04",
        "secret": "6d830d4a75",
        "server": "4354",
        "farm": 5,
        "title": "Serendipity Designs @ SWANK August 2017",
        "ispublic": 1,
        "isfriend": 0,
        "isfamily": 0
      },
      {
        "id": "36087089863",
        "owner": "152685136@N08",
        "secret": "a4a3f2fe0a",
        "server": "4365",
        "farm": 5,
        "title": "Hello Kitty Scooter",
        "ispublic": 1,
        "isfriend": 0,
        "isfamily": 0
      },
      {
        "id": "36086949593",
        "owner": "151818203@N02",
        "secret": "fc1207d373",
        "server": "4334",
        "farm": 5,
        "title": "Hip, Hip! It's Chip!",
        "ispublic": 1,
        "isfriend": 0,
        "isfamily": 0
      },
      {
        "id": "36498504410",
        "owner": "148300038@N02",
        "secret": "5c7f6ff3e1",
        "server": "4391",
        "farm": 5,
        "title": "Hello Kotti",
        "ispublic": 1,
        "isfriend": 0,
        "isfamily": 0
      }
    ]
  },
  "stat": "ok"
}
""".data(using: .utf8)!

let flickrPhotos = try! JSONDecoder().decode(FlickrImageResult.self, from: jsonData)
print(flickrPhotos)

p.s:消息处理json数据时出错：无法读取数据，因为它的格式不正确。是本地化的错误消息，请使用print（错误）而不是print（错误localizeddescription)获取所有可用的错误数据（在您的情况下，它将显示尝试解码场密钥时出现问题）。