How can I print this JSON value in Swift 5? - json

Question

{
"optionChain": {
"result": [
{
"underlyingSymbol": "AAPL",
"expirationDates": [
1606435200,
1607040000,
1607644800,
1608249600,
1608768000,
1609372800,
1610668800,
1613692800,
1616112000,
1618531200,
1623974400,
1626393600,
1631836800,
1642723200,
1655424000,
1663286400,
1674172800
],
"strikes": [
55,
60,
65,
70,
75
],
"hasMiniOptions": false,
How can I print out "underlyingSymbol" or any of those related fields in JSON? I understand printing out a single JSON field, but how do I get into the embedded ones?
So I made the Decodable as Suggested below:
struct Something: Decodable
{
let optionChain: OptionChain
let error: String
}
struct OptionChain: Decodable
{
let result: [ResultElement]
}
struct ResultElement: Decodable
{
let underlyingSymbol: String
let expirationDates: [Int]
let strikes: [Int]
let hasMiniOptions: Bool
let quote: [quoteElement]
let options: [optionsElement]
}
struct quoteElement: Decodable
{
let language: String
let region: String
let quoteType: String
let quoteSourceName: String
let triggerable: Bool
let currency: String
let firstTradeDateMilliseconds: Int
let priceHint: Int
let regularMarketChange: Int
let regularMarketChangePercent: Int
let regularMarketTime: Int
let regularMarketPrice: Int
let regularMarketDayHigh: Int
let regularMarketDayRange: String
let regularMarketDayLow: Int
let regularMarketVolume: Int
let regularMarketPreviousClose: Int
let bid: Int
let ask: Int
let bidSize: Int
let askSize: Int
let fullExchangeName: String
let financialCurrency: String
let regularMarketOpen: Int
let averageDailyVolume3Month: Int
let averageDailyVolume10Day: Int
let fiftyTwoWeekLowChange: Int
let fiftyTwoWeekLowChangePercent: Int
let fiftyTwoWeekRange: String
let fiftyTwoWeekHighChange: Int
let fiftyTwoWeekHighChangePercent: Int
let fiftyTwoWeekLow: Int
let fiftyTwoWeekHigh: Int
let dividendDate: Int
let earningsTimestamp: Int
let earningsTimestampStart: Int
let earningsTimestampEnd: Int
let trailingAnnualDividendRate: Int
let trailingPE: Int
let trailingAnnualDividendYield: Int
let epsTrailingTwelveMonths: Int
let epsForward: Int
let epsCurrentYear: Int
let priceEpsCurrentYear: Int
let sharesOutstanding: Int
let bookValue: Int
let fiftyDayAverage: Int
let fiftyDayAverageChange: Int
let fiftyDayAverageChangePercent: Int
let twoHundredDayAverage: Int
let twoHundredDayAverageChange: Int
let twoHundredDayAverageChangePercent: Int
let marketCap: Int
let forwardPE: Int
let priceToBook: Int
let sourceInterval: Int
let exchangeDataDelayedBy: Int
let tradeable: Bool
let exchange: String
let shortName: String
let longName: String
let marketState: String
let messageBoardId: String
let exchangeTimezoneName: String
let exchangeTimezoneShortName: String
let gmtOffSetMilliseconds: Int
let market: String
let esgPopulated: Bool
let displayName: String
let symbol: String
}
struct optionsElement: Decodable
{
let expirationDate: Int
let hasMiniOptions: Bool
let calls: [callPutElement]
let puts: [callPutElement]
}
struct callPutElement: Decodable
{
let contractSymbol: String
let strike: Int
let currency: String
let lastPrice: Int
let change: Int
let percentChange: Int
let volume: Int
let openInterest: Int
let bid: Int
let ask: Int
let contractSize: String
let expiration: Int
let lastTradeDate: Int
let impliedVolatility: Int
let inTheMoney: Bool
}
However now I am receiving an error:
JSONSerialization error: dataCorrupted(Swift.DecodingError.Context(codingPath: [], debugDescription: "The given data was not valid JSON.", underlyingError: Optional(Error Domain=NSCocoaErrorDomain Code=3840 "No string key for value in object around character 1." UserInfo={NSDebugDescription=No string key for value in object around character 1.})))

Answer 1

I'd use the Codable apis:
struct Something: Decodable {
let optionChain: OptionChain
}
struct OptionChain: Decodable {
let result: [ResultElement]
}
struct ResultElement: Decodable {
let underlyingSymbol: String
let expirationDates: [Int]
let strikes: [Int]
let hasMiniOptions: Bool
}
let jsonString = "{...}"
let jsonData = jsonString.data(using: .utf8)!
let decoder = JSONDecoder()
let something = try decoder.decode(Something.self, from: jsonData)
print(something.optionChain.result.map { $0.underlyingSymbol })