Objects inside Array inside Object Swift

Question

Can somebody help with parsing this kind of JSON object?

{  
   "array":[  
      {  
         "title":"",
         "desc":""
      },
      {  
         "title":"",
         "desc":""
      },
      {  
         "title":"",
         "desc":""
      }
   ]
}

My code doesnt work

let task = self.session.dataTask(with: url) {
        data, response, error in
        if let data = data,
            let json = try? JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] {
            for case let announcment in json!["array"]{
                guard let title = announcment["title"] as? String,
                    let description = announcment["desc"] as? String,
                else{ return }
    }
    task.resume()

Thank in advance for any help!

You should use Codable for Swift 4 and please explain what 'my code doesn't work' means, do you get an error? have you stepped through the code? — Scriptable
– Scriptable, Commented Sep 18, 2018 at 9:00

JonJ · Accepted Answer · 2018-09-17 17:15:25Z

Pretty-printing your JSON makes it easier to work through:

{
   "array":[
      {
         "title":"",
         "desc":""
      },
      {
         "title":"",
         "desc":""
      },
      {
         "title":"",
         "desc":""
      }
   ]
}

You need to get the array first. An array of dictionaries is of type [[String: Any]].

let task = self.session.dataTask(with: url) {
    data, response, error in
    if let data = data,
        let json = try? JSONSerialization.jsonObject(with: data, options: []) as? [String: Any] {
            guard let announcements = json["array"] as? [[String: Any]] 
                else { return }

            announcements.forEach { announcement in
            guard let title = announcement["title"] as? String,
                let description = announcement["desc"] as? String
                else { return }
            // Do something with the result
            }
       }
  }
task.resume()

Leo Dabus · Accepted Answer · 2018-09-17 17:28:08Z

1

You can structure your data and make it Codable:

struct Root: Codable {
    let array: [Announcement]
}
struct Announcement: Codable {
    let title: String
    let desc: String
}

let data = Data("""
{"array":[{"title":"","desc":""},{"title":"","desc":""},{"title":"","desc":""}]}
""".utf8)

do {
    let announcements = try JSONDecoder().decode(Root.self, from: data).array
    for announcement in announcements {
        print(announcement)
    }
} catch {
    print(error)
}

This will print

Announcement(title: "", desc: "")
Announcement(title: "", desc: "")
Announcement(title: "", desc: "")

edited Sep 17, 2018 at 17:28

answered Sep 17, 2018 at 17:20

Leo Dabus

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1 Comment

Virtual Device Over a year ago

Thanks for the answer. I didn't know about Cadable :)

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