CODEWITHSUNDEEP
jsonswiftcodable
KingTim
KingTim

Reputation: 1301

Error when serializing JSON "keyNotFound"

I'm practicing the new way of parsing JSON in Swift 4 and I'm using the New York Times API - I'm finding it hard to read the structure of the JSON since the API page just shows a wall of text

I've written out a small struct for the data I want to pull (titles, abstracts):

struct Stories: Decodable {
    let title: String
    let abstract: String
}

and here's the function I call to get the JSON:

func getJSON() {
    let jsonUrlString = "https://api.nytimes.com/svc/topstories/v1/business.json?api-key=f4bf2ee721031a344b84b0449cfdb589:1:73741808"
    guard let url = URL(string: jsonUrlString) else {return}

    URLSession.shared.dataTask(with: url) { (data, response, err) in

        guard let data = data else {return}

        do {

            let stories = try
                JSONDecoder().decode(Stories.self, from: data)
            print(stories.title, stories.abstract)

        } catch let jsonErr {
            print("Error serializing JSON", jsonErr)
        }
    }.resume()
}

When I run the app, I see my error message in the console:

Error serializing JSON keyNotFound(CodingKeys(stringValue: "title", intValue: nil), Swift.DecodingError.Context(codingPath: [], debugDescription: "No value associated with key CodingKeys(stringValue: \"title\", intValue: nil) (\"title\").", underlyingError: nil))

So it looks like it's not finding the values of "title". What can I do differently here, did I set up the Struct incorrectly? Or am I using JSONDecorder wrong?

Thanks for any help!

Upvotes: 0

Views: 533

Answers (1)

David Pasztor
David Pasztor

Reputation: 54706

The issue is that the Stories are nested in an outer Dictionary, which you also need to parse.

struct TopStoriesResponse: Codable {
    let status:String
    let results:[Story]
}

struct Story: Codable {
    let title: String
    let abstract: String
}

func getTopStories() {
    let jsonUrlString = "https://api.nytimes.com/svc/topstories/v1/business.json?api-key=f4bf2ee721031a344b84b0449cfdb589:1:73741808"
    guard let url = URL(string: jsonUrlString) else {return}

    URLSession.shared.dataTask(with: url) { (data, response, err) in

        guard let data = data, err == nil else {
            print(err!)
            return
        }

        do {
            let response = try JSONDecoder().decode(TopStoriesResponse.self, from: data)
            print(response.results.first?.title, response.results.first?.abstract)

        } catch let jsonErr {
            print("Error serializing JSON", jsonErr)
        }
    }.resume()
}

Upvotes: 1

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