Parsing Nested JSON SWIFT 4 - ios

Question

Could anyone tell me what I am doing wrong?
Here is JSON I'm trying to parse:
{
"results": {
"AF": {
"alpha3": "AFG",
"currencyId": "AFN",
"currencyName": "Afghan afghani",
"currencySymbol": "؋",
"id": "AF",
"name": "Afghanistan"
},
"AI": {
"alpha3": "AIA",
"currencyId": "XCD",
"currencyName": "East Caribbean dollar",
"currencySymbol": "$",
"id": "AI",
"name": "Anguilla"
}
}
}
My code :
class Results: Codable {
let results: [Country]
init(results: [Country]) {
self.results = results
}
}
class Country: Codable {
let currencyId: String
let currencyName: String
let currencySymbol: String
let id: String
let name: String
init(currencyId :String, currencyName: String, currencySymbol: String, id: String, name: String ) {
self.currencyId = currencyId
self.currencyName = currencyName
self.currencySymbol = currencySymbol
self.id = id
self.name = name
}
}
I have looked at Apple's Documentation on decoding nested structs, but I still do not understand how to do the different levels of the JSON properly.
Thanks.

Answer 1

Check the outlined value for the key "results".
"results": {
...
}
{...} represents JSON object. A Swift struct (or class if you think it's better) would be appropriate for JSON object in some cases.
In other cases, Swift Dictionary may be more appropriate.
And each value of this JSON object takes this form:
{
"alpha3": ...,
"currencyId": ...,
"currencyName": ...,
"currencySymbol": ...,
"id": ...,
"name": ...
}
which matches your Country.
So, you just need to change the type of results in your Results class.
class Results: Codable {
let results: [String: Country]
init(results: [String: Country]) {
self.results = results
}
}
Having the same name (without case) for a property and its class might cause some confusion in the future, but I keep it as is as for now.
You can test it like this:
(Assuming to be tested in the Playground with modified Results and your Country.)
let jsonText = """
{
"results": {
"AF": {
"alpha3": "AFG",
"currencyId": "AFN",
"currencyName": "Afghan afghani",
"currencySymbol": "؋",
"id": "AF",
"name": "Afghanistan"
},
"AI": {
"alpha3": "AIA",
"currencyId": "XCD",
"currencyName": "East Caribbean dollar",
"currencySymbol": "$",
"id": "AI",
"name": "Anguilla"
}
}
}
"""
let jsonData = jsonText.data(using: .utf8)!
let decoder = JSONDecoder()
do {
let results = try decoder.decode(Results.self, from: jsonData)
print(results) //-> __lldb_expr_1.Results
} catch {
print(error)
}