How to decode .keys from dictionary using Coadable - ios

Question

I have a below JSON response. And I want to fetch the allkeys of “data” which is [“rules”, “preference”, “goals”] using .keys method. But I couldn’t get the array of allkeys using .keys feature. I have attached my code snippet also. if you had faced this one, please suggest me to rid of this concern.
Although, I can get these allKeys using ObjectMapper and native Dictionary objects. I just need to know why I couldn't achieve this using Codable.
My json response
{
"statusCode": 200,
"status": "success",
"message": null,
"data": {
"rules": {
"goals": {
"min": "1",
"max": "3"
}
},
"preference": [
1,
2,
3
],
"goals": {
"total": 4,
"data": []
}
}
}
My code Snippet:
struct MeetingsDataModal: Codable {
let statusCode: Int?
let status: String?
let message: String?
let data: Results?
enum CodingKeys: String, CodingKey {
case statusCode = "statusCode"
case status = "status"
case message = "message"
case data = "data"
}
func allkeys() {
}
}
struct Results : Codable {
let rules: Rules?
let preference: [Preference]?
let goals: Goals?
enum CodingKeys: String, CodingKey {
case rules = "rules"
case preference = "preference"
case goals = "goals"
}
}
struct Rules : Codable {
}
struct Preference : Codable {
}
struct Goals : Codable {
}
My expectation
let content = try JSONDecoder().decode(MeetingsDataModal.self, from: (response as? Data)!)
print(content.data.keys)
But I am getting,
Value of type 'Results?' has no member 'keys'

Answer 1

Perhaps I am not understanding the question well but your "keys" are defined by your Codable protocol - so they are known. If you are using Swift 4.2+ you can take advantage of the CaseIterable protocol
struct Results: Codable {
let testOne: Int
let testTwo: String
enum CodingKeys: String, CodingKey, CaseIterable {
case testOne
case testTwo
}
}
Results.CodingKeys.allCases.map { $0.rawValue }

Answer 2

If you do need .keys. could add two-line code :
struct Results : Codable {
let rules: Rules?
let preference: [Preference]?
let goals: Goals?
enum CodingKeys: String, CodingKey {
case rules = "rules"
case preference = "preference"
case goals = "goals"
}
var keys : [String]{
return["rules", "preference","goals"]
}
}
Actually, if you don't like encoding/decoding way , we have another traditional JSON object can help you to handle unstructured JSON.
let obj = try JSONSerialization.jsonObject(with: response!, options: JSONSerialization.ReadingOptions.allowFragments)
print((((obj as! [String: Any?])["data"]) as! [String: Any?]).keys)
Here is one way to decode you data structure.
let d = """
{
"statusCode": 200,
"status": "success",
"message": null,
"data": {
"rules": {
"goals": {
"min": "1",
"max": "3"
}
},
"preference": [
1,
2,
3
],
"goals": {
"total": 4,
"data": []
}
}
}
""".data(using: .utf8)!
struct MeetingsDataModal: Decodable {
let statusCode: Int
let status: String
let message: String?
let data: Results
}
struct Results : Decodable {
let rules: Rules
let preference: [Int]
let goals: Goals
}
struct Rules : Decodable {
let goals : DirectData
}
struct DirectData : Decodable{
let min : String
let max : String
}
struct Goals : Decodable {
let total : Int
let data : [String]
}
let data0 = try JSONDecoder().decode(MeetingsDataModal.self, from: d)
print(data0)