How do I parse this JSON API data in SwiftUI? - json

Question

A beginner here.
I'm having some trouble trying to parse this json url in SwiftUI
Here is what I've tried:
import SwiftUI
struct PriceData2: Decodable {
var id: Int
var last: Double
var lowestAsk: Double
var highestBid: Double
var percentChange: Double
var baseVolume: Double
var quoteVolume: Double
var isFrozen: Int
var high24hr: Double
var low24hr: Double
var change: Double
var prevClose: Double
var prevOpen: Double
}
struct ContentView: View {
#State var priceData2: PriceData2?
var body: some View {
if #available(iOS 15.0, *) {
VStack(){
Text("\(priceData2?.id ?? 0)")
}.onAppear (perform: loadData2)
} else {
// Fallback on earlier versions
}
}
public func loadData2() {
guard let url = URL(string: "https://api.bitkub.com/api/market/ticker?sym=THB_BTC") else {
return
}
URLSession.shared.dataTask(with: url) { data, response, error in
guard let data = data else {return}
if let decodedData = try? JSONDecoder().decode(PriceData2.self, from: data){
DispatchQueue.main.async {
self.priceData2 = decodedData
}
}
}.resume()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
I think it has something to do with the THB_BTC property of the dictionary that I haven't dealt with but I'm not totally sure of.
Any help with this is much appreciated.
Thanks

Answer 1

What is missing when decoding is a top level type to hold the price data and there are two ways to solve this, either by using a top level struct or by using a dictionary.
Since the top level key, THB_BTC, seems to be the "symbol" argument from the query and thus might change a top level dictionary is the best alternative here
do {
let result = try JSONDecoder().decode([String: PriceData].self, from: data)
if let priceData = result.values.first { //or = result["THB_BTC"]
print(priceData)
}
} catch {
print(error)
}
Just for completeness, here is the variant with the top level struct
struct Result: Decodable {
enum CodingKeys: String, CodingKey {
case data = "THB_BTC"
}
let data: PriceData
}
let result = try JSONDecoder().decode(Result.self, from: data)
print(result.data)