Swift Codable to parse JSON with dynamic keys - ios

Question

I am trying to parse the below JSON response, which has multiple dynamic keys,
{
"Nagaland": {
"districtData": {
"Dimapur": {
"confirmed": 1,
"lastupdatedtime": "",
"delta": {
"confirmed": 0
}
}
}
},
"Meghalaya": {
"districtData": {
"East Khasi Hills": {
"confirmed": 1,
"lastupdatedtime": "",
"delta": {
"confirmed": 0
}
}
}
}
}
I have written my Codable struct like below,,
struct IndianStateListModel: Codable {
// MARK: Properties
let state: [String: StateData]
}
struct StateData: Codable {
// MARK: Properties
var districtData: Inner?
/// Mapping Key Enum
private enum CodingKeys: String, CodingKey {
case districtData
}
}
struct Inner: Codable {
// MARK: Properties
let districts: [String: DistrictData]
}
struct DistrictData: Codable {
// MARK: Properties
var confirmed: Int?
var lastupdatedtime: String?
var delta: DailyConfirmedData?
/// Mapping Key Enum
private enum CodingKeys: String, CodingKey {
case confirmed, lastupdatedtime, delta
}
}
struct DailyConfirmedData: Codable {
// MARK: Properties
var confirmed: Int?
/// Mapping Key Enum
private enum CodingKeys: String, CodingKey {
case confirmed
}
}
It's called as,
let summary = try JSONDecoder().decode(IndianStateListModel.self, from: data)
But its returning nil
P.S.: related question regarding decodable Swift Codable with dynamic keys
Any solution, would be great, Thanks in advance

Answer 1

The Codable models that you must use to parse the above JSON data should be like,
Models:
struct StateData: Codable {
var districtData: [String:DistrictData]?
}
struct DistrictData: Codable {
var confirmed: Int?
var lastupdatedtime: String?
var delta: DailyConfirmedData?
}
struct DailyConfirmedData: Codable {
var confirmed: Int?
}
Parsing:
let summary = try JSONDecoder().decode([String:StateData].self, from: data)
Note: There is no need to explicitly create enum CodingKeys if the JSON keys exactly match the properties of the Codable type.

Answer 2

The fundamental issue is that IndianStateListModel has a property called states. But no such key appears in your JSON. I’d suggest parsing it with singleValueContainer. E.g. perhaps:
struct States: Decodable {
typealias StateName = String
let states: [StateName: Districts]
init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
states = try container.decode([StateName: Districts].self)
}
}
struct Districts: Decodable {
typealias DistrictName = String
var districts: [DistrictName: DistrictData]
enum CodingKeys: String, CodingKey {
case districts = "districtData"
}
}
struct DistrictData: Decodable {
var confirmed: Int
var lastupdatedtime: String
var delta: DailyConfirmedData
}
struct DailyConfirmedData: Decodable {
var confirmed: Int?
}
And
do {
let result = try JSONDecoder().decode(States.self, from: data)
print(result)
} catch {
print(error)
}