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

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?

Answer 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)
}

Answer 2

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