How to parse a multi-level json structure in Swift?

Question

The JSON from server looks like this:

A dictionary where the value is another dictionary.

{
    "S1": {
        "vpn_status": 2,
        "vpn_name": "vpn1"
    },
    "S2": {
        "vpn_status": 1,
        "vpn_name": "vpn2"
    }
}

I have created the following struct to parse it.

public struct ServerStatusResult {

    public let vpnName: String
    public let status: Int

    init?(json: [String: Any]) {
        guard
            let vpnName = json["vpn_name"] as? String,
            let status = json["vpn_status"] as? Int
            else {
                return nil
        }
        self.vpnName = vpnName
        self.status = status
    }
}

And the function to call the server is:

typealias serverStatusCompletedClosure = (_ status: Bool, _ result: Dictionary<String,ServerStatusResult>?, _ error: ServiceError?)->Void

func serverStatus(email: String, password: String, complete: @escaping serverStatusCompletedClosure) {
        let url = URL(string: "...")!
        try? self.httpClient.get(url: url,
                                token: "...",
                                email: email,
                                password: password)
        { (data, response, error) in
            if let error = error {
                complete(false, nil, ServiceError.invalidSession)
            } else if let httpResponse = response as? HTTPURLResponse {
                switch (httpResponse.statusCode) {
                case 200:
                    var result: [String:ServerStatusResult]? = nil
                    result = try! JSONSerialization.jsonObject(with: data!, options: []) as! Dictionary<String, ServerStatusResult>
                    complete(true, result, nil)

This is where my json transformation fails.

Could not cast value of type '__NSDictionaryI' (0x7fff8eaee9b0) to 'app.ServerStatusResult' (0x10021dec0).

What am I missing please?

Why not use Decodable and decode a dictionary [String: ServerStatusResult]? ` — Joakim Danielson
– Joakim Danielson, Commented Apr 3, 2020 at 8:22
Are you sure the response? Because the response which you shared is not has a type like [String: ServerStatusResult] if it is you missed something because I couldn't see any [ ] between String to ServerStatusResult fields — emrcftci
– emrcftci, Commented Apr 3, 2020 at 8:26
is there a fix number of dict inside the main dictionary or it can be any? — Suryakant Sharma
– Suryakant Sharma, Commented Apr 3, 2020 at 8:26

Joakim Danielson · Accepted Answer · 2020-04-03 08:31:10Z

1

You can solve it by using Decodable and using a dictionary

First make your struct conform to Decodable

public struct ServerStatusResult: Decodable {
    public let vpnName: String
    public let status: Int

    enum CodingKeys: String, CodingKey {
        case vpnName = "vpn_name"
        case status = "vpn_status"
    }
}

and then the decoding is easy

do {
    let result = try JSONDecoder().decode([String: ServerStatusResult].self, from: data)
    print(result) //or in you case complete(true, result, nil)
} catch {
    print(error)
}

answered Apr 3, 2020 at 8:31

Joakim Danielson

53.1k5 gold badges36 silver badges79 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Arun Srithar · Accepted Answer · 2020-04-03 08:25:57Z

0

You get an array of dictionary [[String: Any]]

Create a struct for a dictionary and if a dictionary has another dictionary inside it then create another struct for the inner Dictionary and create an object in the outer struct for innner dictionary json.

You can use codeable to parse your json easily, by inheriting your struct with codeable

answered Apr 3, 2020 at 8:25

Arun Srithar

786 bronze badges

Collectives™ on Stack Overflow

How to parse a multi-level json structure in Swift?

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related