Connect one JSON to another

Question

I've got these 2 JSON that share a field userId

This one:

{
    "oldest": "2019-01-24T00:00:00+00:00",
    "activities": [
        {
            "message": "<strong>Henrik</strong> didn't resist a guilty pleasure at <strong>Starbucks</strong>.",
            "amount": 2.5,
            "userId": 2,
            "timestamp": "2019-05-23T00:00:00+00:00"
        },
        {
            "message": "<strong>Johan</strong> made a roundup.",
            "amount": 0.32,
            "userId": 3,
            "timestamp": "2019-05-22T00:00:00+00:00"
        },
        {
            "message": "<strong>You</strong> didn't resist a guilty pleasure at <strong>Starbucks</strong>.",
            "amount": 15,
            "userId": 1,
            "timestamp": "2019-05-21T00:00:00+00:00"
        }
]

And this one:

[
    {
        "userId": 1,
        "displayName": "Mikael",
        "avatarUrl": "http://qapital-ios-testtask.herokuapp.com/avatars/mikael.jpg"
    },
    {
        "userId": 2,
        "displayName": "Henrik",
        "avatarUrl": "http://qapital-ios-testtask.herokuapp.com/avatars/henrik.jpg"
    },
    {
        "userId": 3,
        "displayName": "Johan",
        "avatarUrl": "http://qapital-ios-testtask.herokuapp.com/avatars/johan.jpg"
    },
    {
        "userId": 4,
        "displayName": "Erik",
        "avatarUrl": "http://qapital-ios-testtask.herokuapp.com/avatars/erik.jpg"
    },
    {
        "userId": 5,
        "displayName": "George",
        "avatarUrl": "http://qapital-ios-testtask.herokuapp.com/avatars/george.jpg"
    },
    {
        "userId": 6,
        "displayName": "Daniel",
        "avatarUrl": "http://qapital-ios-testtask.herokuapp.com/avatars/daniel.jpg"
    }
]

Now I have the first one sorted out like this:

struct Root: Decodable {
    var oldest: Date
    var activities: [Activity]
}

struct Activity: Decodable {
    var message: String
    var amount: Float
    var userId: Int
    var timestamp: Date
}

Notice that the userId var in Activity (1st JSON) also appears on the 2nd JSON. I'm using these structs to populate my TableViewController.

What I ultimately need is to have the avatar image show up next to the message and date label (check image). For this I think I would need to connect/relate (don't know the word for it) the 1st JSON with the 2nd JSON, correct me if I'm wrong. Would I also need another struct for User?

This is my networking code:

let userJSONURLString = "https://qapital-ios-testtask.herokuapp.com/users"
        let activitiesJSONURLString = "https://qapital-ios-testtask.herokuapp.com/activities?from=2016-05-23T00:00:00+00:00&to=2019-05-23T00:00:00+00:00"
        guard let userURL = URL(string: userJSONURLString) else { return }
        guard let activitiesURL = URL(string: activitiesJSONURLString) else { return }

        URLSession.shared.dataTask(with: activitiesURL) { (data, response, err) in
            // perhaps check err
            // also perhaps check response status 200 OK

            guard let data = data else { return }

            do {
                // Activities
                let decoder = JSONDecoder()
                decoder.dateDecodingStrategy = .iso8601
                let result = try decoder.decode(Root.self, from: data)
                self.activities = result.activities

                DispatchQueue.main.async {
                    self.tableView.reloadData()
                }
            } catch {
                print("Error serializing json: ", error)
            }

        }.resume()

And this is my cellForRowAt (if you need it):

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "ActivityCell", for: indexPath) as! MainTableViewCell
        let activity = activities[indexPath.row]

        // Amount
        cell.amountLabel.text = String(format: "$%.2f", activity.amount)

        // Message
        let formattedString = activity.message.htmlAttributedString().with(font:UIFont(name: "Helvetica Neue", size: 15)!)
        cell.descriptionLabel.attributedText = formattedString

        // Date
//        cell.dateLabel

        // Avatar


        return cell
    }

Updated code:

struct Activity: Decodable {
    var message: String
    var amount: Float
    var userId: Int
    var timestamp: Date
    var avatar : UIImage = UIImage(named: "user-icon-image-placeholder-300-grey.jpg")!
    private enum CodingKeys : String, CodingKey { case message, amount, userId, timestamp }
}

---

URLSession.shared.dataTask(with: activitiesURL) { (data, response, err) in
            guard let data = data else { return }
            do {
                // Activities
                let decoder = JSONDecoder()
                decoder.dateDecodingStrategy = .iso8601
                let result = try decoder.decode(Root.self, from: data)
                self.activities = result.activities

                URLSession.shared.dataTask(with: userURL) { (data, response, err) in
                    guard let data = data else { return }
                    do {
                        // Users
                        let usersJson = try JSONSerialization.jsonObject(with: data, options: [])
                        guard let jsonArray = usersJson as? [[String: Any]] else { return }

                        for dic in jsonArray {
                            guard let avatarUrl = dic["avatarUrl"] as? String else { return }
                            print(avatarUrl)
                        }

                    } catch {
                        print("Error serializing json: ", error)
                    }
                    }.resume()
            } catch {
                print("Error serializing json: ", error)
            }

            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        }.resume()

Answer 1

• In the Activity struct add CodingKeys and an extra member for the avatar URL

  struct Activity: Decodable {
      let message: String
      let amount: Float
      let userId: Int
      let timestamp: Date
  
      var avatar : URL = // some default URL to a placeholder image on disk
  
      private enum CodingKeys : String, CodingKey { case message, amount, userId, timestamp }
  } 
  

  The purpose of the CodingKeys is that only the first 4 struct members are decoded.

• In the completion handler of the first data task add a second data task to load the user data.

• Decode the JSON as array of dictionaries with JSONSerialization.
• In a loop get the activity for the given userId and update the avatar URL.
• Then reload the table view.
• To load the avatar images you need a logic to download and cache the images asynchronously.