Swift 4 json decoder error flickr

Question

I am trying out the new JSONDecoder() in swift 4 and am trying to parse the following flickr API response : (https://api.flickr.com/services/rest/?api_key=api_key&method=flickr.photos.search&format=json&per_page=25&text=hello&nojsoncallback=1). However I get an error saying that "error processing json data: The data couldn’t be read because it isn’t in the correct format." However the data seems to be in the correct format to me. Am I doing anything wrong?

            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()

My data models are

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
}

I changed the number of images requested to 2 and Printing out the data returns Optional({"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","owner":"141041947@N06","secret":"bc0e5af630","server":"4380","farm":5,"title":"POST\ud83d\udd25 #891 | Hello Tuesday | Krescendo","ispublic":1,"isfriend":0,"isfamily":0}]},"stat":"ok"})

Does it show the correct JSON string if you just print the `data` from the URL response? — Paolo, Aug 29 '17 at 19:16
So the response is returning 200 and printing data returns 4694 bytes so I assume there is something there. — masterqp, Aug 29 '17 at 19:20
try `print(String(bytes:data, encoding: .utf8) )` to see what's actually there — Joshua Breeden, Aug 29 '17 at 19:23
I was just doing that thanks! And it does return the correct data I added it to the question. — masterqp, Aug 29 '17 at 19:25
It looks like it thinks `data` is optional even though you unwrapped it. Try using a different name such as `else if let jsonData = data {` and then change `data` to `jsonData` in your `decode(...)` call. — Paolo, Aug 29 '17 at 19:35

nathan · Accepted Answer · 2017-08-29T20:43:50.567

The only problem with your model is that farm is actually an Int. Here's a more complete version of your model accoirding to the docs (https://www.flickr.com/services/api/flickr.photos.search.html):

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: The message error processing json data: The data couldn’t be read because it isn’t in the correct format. is the localized error message, use print(error) instead of print(errorlocalizedDescription) to obtain all the error data available (in your case, it will print that there's an issue when trying to decode the farm key).

Hey thanks so much for your help. However when I plug in the above and put it in a do catch block it still give me the error "The data couldn’t be read because it isn’t in the correct format." Could it be a swift 4 problem? do { let flickrPhotos = try JSONDecoder().decode(FlickrImageResult.self, from: jsonData) print(flickrPhotos) } catch { print(error.localizedDescription) } — masterqp, Aug 29 '17 at 19:40
The whole example works: Check here for live eval http://swift.sandbox.bluemix.net/#/repl/59a5c3e452eabe5bb8de608f (Playgrounds/Empty iOS app also) — nathan, Aug 29 '17 at 19:43
Nevermind, it was a JSON encoding issue (farm is an Int not String). When you are debugging, never use `error.localizedDescription` but `print("json error: \(error)")` instead. It will provide more information. — nathan, Aug 29 '17 at 19:55
The only issue with your model was that farm needs to be an Int (answer updated). — nathan, Aug 29 '17 at 19:58

Swift 4 json decoder error flickr

1 Answers1