I'm working on an app that requires the use of the TMDB API. I have been trying to store the results from the API in a struct but it keeps giving me the error:
No exact matches in call to subscript
This is the struct:
struct MovieList: Codable {
let dates: Date?
let page: Int?
let results: [Result]?
let total_pages: Int?
let total_results: Int?
}
struct Result: Codable {
let adult: Bool?
let backdrop_path: String?
let genre_ids: [Int]?
let id: Int?
let original_language: String?
let original_title: String?
let overview: String?
let popularity: Int?
let poster_path: String?
let release_date: String?
let title: String?
let video: Bool?
let vote_average: Float?
let vote_count: Int?
And here is my API call:
public class LoadTMDBData {
var tmdbMoviesData = [[Result]]()
init() {
getTMDBData()
}
func getTMDBData() {
guard let url = URL(string: "") else {
fatalError("Invalid URL")
}
// Set session configuration to default
let config = URLSessionConfiguration.default
let session = URLSession(configuration: config)
let task = session.dataTask(with: url) { data, response, error in
// Check that data has been returned
guard let data = data else { return }
do {
let tmdbData = try JSONDecoder().decode([MovieList].self, from: data)
self.tmdbMoviesData = tmdbData["result"]
}
catch{
let error = error
print(error.localizedDescription)
}
}
// execute the HTTP request
task.resume()
}
When using a struct you don't access its properties using a string key like ["someProperty"], instead you use dot notation .someProperty, so to get the results property you do
let results = myMoveList.results
What makes it a little more complicated here is that you have, as you properly have coded for, an array of MovieList and that you want to extract all results into an array for array.
For this you can use a high order function map to do this
self.tmdbMoviesData = tmdbData.map(\.results)
but since results is optional we use a similar function that will filter out any nil values, compactMap
self.tmdbMoviesData = tmdbData.compactMap(\.results)
Another comment, you have made all properties optional in your structs and while this is an easy way forward it might lead to hiding some decoding issues and more cumbersome code when using the types. I would recommend not to use optional unless really needed.
Related
I am making a project in Swift with MVVM design. I want to get coin name, current price, Rank and Symbol from a Crypto site. I can't show the json data I get on the console. The model is in another folder because I did it with MVVM. How can I create a struct to get the data here? You can find screenshots of my project below. I would be glad if you help.
Below are the codes I wrote in my web service file
import Foundation
class WebService {
func downloadCurrencies(url: URL, completion: #escaping ([DataInfo]?) -> ()) {
URLSession.shared.dataTask(with: url) { (data, response, error) in
if let error = error {
print(error.localizedDescription)
completion(nil)
} else if let data = data {
let cryptoList = try? JSONDecoder().decode([DataInfo].self, from: data)
print(cryptoList)
if let cryptoList = cryptoList {
completion(cryptoList)
}
}
}
.resume()
}
}
Below are the codes I wrote in my model file
import Foundation
struct DataInfo : Decodable {
var name: String
var symbol: String
var cmc_rank: String
var usd: Double
}
Finally, here is the code I wrote to print the data in the viewController to my console. But unfortunately I can't pull the data.
override func viewDidLoad() {
super.viewDidLoad()
let url = URL(string: "https://pro-api.coinmarketcap.com/v1/cryptocurrency/listings/latest?start=1&limit=10&convert=USD&CMC_PRO_API_KEY=5ac24b80-27a1-4d01-81bd-f19620533480")!
WebService().downloadCurrencies(url: url) { cryptos in
if let cryptos = cryptos {
print(cryptos)
}
}
}
I've seen your URL and tested it ON Postman and also i've got your code and tried to put it in a shape, the code is good, but it can't MAP JSON Data against your struct because this is the json Data from Postman
Postman Data
While Looking at your Struct, It Doesnt Match the format of JSON Data you're receiving,
Struct
Well, To Make your structure match the JSON String you need to create Nested String: Any Dictionary. But there's another issue with the logic, you need to decode data outside of the webservice call because it can contain errors which wont be mapped in the struct and can handle if you get other statusCode.
If you try to implement all these things manually, the code will become complex and hard to understand. I would rather recommend you to use Alamofire with SwiftyJSON and it can make your work a lot shorter and easier and understandable.
Sorry for the bad english.
Your api-key is not valid for me.
Your data must be inside of object or invalid keys and you are surely missing it thats why it is not parsing correctly.
My suggestion is to put your json response in this website
"https://app.quicktype.io/"
and replace your struct with new one, you will be good to go hopefully.
Your models does not have 1 to 1 correspondence with the response object. The root object is not a [DataInfo], but another structure that contains an array of DataInfos. Here are the correct models
struct Response: Codable {
let status: Status
let data: [CurrencyData]
}
struct Status: Codable {
let creditCount: Int
let elapsed: Int
let timestamp: String
let totalCount: Int
let errorCode: Int?
let errorMessage: String?
let notice: String?
enum CodingKeys: String, CodingKey {
case notice
case timestamp
case elapsed
case creditCount = "credit_count"
case errorCode = "error_code"
case errorMessage = "error_message"
case totalCount = "total_count"
}
}
enum Currency: String, Codable, Hashable {
case usd = "USD"
}
struct CurrencyData: Codable {
let circulatingSupply: Double?
let cmcRank: Int
let dateAdded: String?
let id: Int
let lastUpdated: String?
let maxSupply: Int?
let name: String
let numMarketPairs: Int
let platform: Platform?
let quote: [String: Price]
let selfReportedCirculatingSupply: String?
let selfReportedMarketCap: String?
let slug: String
let symbol: String
let tags: [String]?
let totalSupply: Double
func price(for currency: Currency) -> Double? {
return quote[currency.rawValue]?.price
}
enum CodingKeys: String, CodingKey {
case id
case name
case platform
case quote
case slug
case symbol
case tags
case circulatingSupply = "circulating_supply"
case cmcRank = "cmc_rank"
case dateAdded = "date_added"
case lastUpdated = "last_updated"
case maxSupply = "max_supply"
case selfReportedCirculatingSupply = "self_reported_circulating_supply"
case selfReportedMarketCap = "self_reported_market_cap"
case totalSupply = "total_supply"
case numMarketPairs = "num_market_pairs"
}
}
struct Price: Codable {
let fullyDilutedMarketCap: Double?
let lastUpdated: String?
let marketCap: Double?
let marketCapDominance: Double?
let percentChange1h: Double?
let percentChange24h: Double?
let percentChange30d: Double?
let percentChange60d: Double?
let percentChange7d: Double?
let percentChange90d: Double?
let price: Double?
let volume24h: Double?
let volumeChange24h: Double?
enum CodingKeys: String, CodingKey {
case price
case fullyDilutedMarketCap = "fully_diluted_market_cap"
case lastUpdated = "last_updated"
case marketCap = "market_cap"
case marketCapDominance = "market_cap_dominance"
case percentChange1h = "percent_change_1h"
case percentChange24h = "percent_change_24h"
case percentChange30d = "percent_change_30d"
case percentChange60d = "percent_change_60d"
case percentChange7d = "percent_change_7d"
case percentChange90d = "percent_change_90d"
case volume24h = "volume_24h"
case volumeChange24h = "volume_change_24h"
}
}
struct Platform: Codable {
let id: Int
let name: String
let symbol: String
let slug: String
let tokenAddress: String?
enum CodingKeys: String, CodingKey {
case id
case name
case symbol
case slug
case tokenAddress = "token_address"
}
}
and you can retrieve the cryptoList in your completion handler like this:
let cryptoList = (try? JSONDecoder().decode([Response].self, from: data))?.data
Also it's not safe to expose your personal data to the internet (API_KEY, etc.)
I’m trying to loading the content from a JSON that I created, but unfortunately it doesn’t work.
As you can see from the code below, the only thing I see is “Error” printed in the console.
I also tried with other JSONs from the web, changing the struct accordingly, and it works, but not with the JSON I created.
Here is the code:
import SwiftUI
import URLImage
struct Busso: Codable, Identifiable {
public var id: UUID
public var titolo: String
public var autore: String
public var testo: String
public var data: String
public var extra1: String
public var extra2: String
public var foto: String
public var fotoUrl: String
}
class FetchBusso: ObservableObject {
#Published var Bussos = [Busso]()
init() {
let url = URL(string: "https://geniuspointfrezza.altervista.org/index.php?json=1")!
URLSession.shared.dataTask(with: url) {(data, response, error) in
do {
if let bussoData = data {
let decodedData = try JSONDecoder().decode([Busso].self, from: bussoData)
DispatchQueue.main.async {
self.Bussos = decodedData
}
} else {
print("No data")
}
} catch {
print("Error")
}
}.resume()
}
}
struct CategoryView: View {
#ObservedObject var fetch = FetchBusso()
var body: some View {
VStack {
List(fetch.Bussos) { todo in
VStack(alignment: .leading) {
Text(todo.titolo)
}
}
}
}
}
struct CategoryView_Previews: PreviewProvider {
static var previews: some View {
CategoryView()
}
}
And here is the link to the JSON I want to use:
https://geniuspointfrezza.altervista.org/index.php?json=1
Waiting for your advice, thank you!
Json I'm throwing the site to help you read. You can get help at the point where you get stuck.shttps: //app.quicktype.io
The issue is
public var id: UUID your JSON is public var id: String
catch {
print(error)
}
is more useful than
print("Error")
Your Busso struct is not a proper decoder for the given JSON. As I gave you the link to a prior one of my answers that explains how to get a struct that will parse your data. You really need to review that, but for the sake of putting this to bed, the struct should be:
// MARK: - GeniuspointfrezzaDecoder
struct GeniuspointfrezzaDecoder: Codable {
let id: String?
let titolo: String?
let autore: String?
let testo: String?
let data: String?
let extra1: String?
let extra2: String?
let creazione: String?
let foto: String?
let fotoURL: String?
enum CodingKeys: String, CodingKey {
case id, titolo, autore, testo, data, extra1, extra2, creazione, foto
case fotoURL = "fotoUrl"
}
}
I made the elements all optional since you don't actually know if the server response will contain all of the elements. Another issue you had was declaring the id in your decoder to be a UUID, when the JSON response is clearly a string. Changing the response data to your app's needs has to be done AFTER decoding the response. The decoder is NOT your Busso struct. It is a decoder that gives you the data to put into your Busso struct.
I have been trying to get this code to work for like 6 hours. I get the error: "failed to convert The data couldn’t be read because it is missing." I don't know while the File is missing is there something wrong in my models(structs). Do I need to write a struct for very json dictionary? Currently I have only made those JSON dictionaries to a struct, which I actually need. The full JSON file can be found at https://api.met.no/weatherapi/sunrise/2.0/.json?lat=40.7127&lon=-74.0059&date=2020-12-22&offset=-05:00 . I want to be able to print the time of the sunrise, sunset and solar noon as well as the elevation of the sun at solar noon. It's currently 1 am and I am desperate. Good Night!
class ViewController: NSViewController {
#IBOutlet weak var sunriseField: NSTextField!
#IBOutlet weak var sunsetField: NSTextField!
#IBOutlet weak var daylengthField: NSTextField!
override func viewDidLoad() {
super.viewDidLoad()
let url = "https://api.met.no/weatherapi/sunrise/2.0/.json?lat=40.7127&lon=-74.0059&date=2020-12-22&offset=-05:00"
getData(from: url)
// Do any additional setup after loading the view.
}
private func getData(from url: String) {
let task = URLSession.shared.dataTask(with: URL(string: url)!, completionHandler: {data, response, error in
guard let data = data, error == nil else {
print("something went wrong")
return
}
var result: MyTime?
do {
result = try JSONDecoder().decode(MyTime.self, from: data)
}
catch {
print("failed to convert \(error.localizedDescription)")
}
guard let json = result else {
return
}
let sunrise1 = json.sunrise.time
DispatchQueue.main.async { [weak self] in
self?.sunriseField.stringValue = sunrise1
}
print(json)
})
task.resume()
}
override var representedObject: Any? {
didSet {
// Update the view, if already loaded.
}
}
}
struct MyData : Codable {
let location : Location
let meta : Meta
}
struct MyTime : Codable {
let solarnoon : Solarnoon
let sunset : Sunset
let sunrise : Sunrise
}
struct Location : Codable {
let height : String
let time : [MyTime]
let longitude : String
let latitude : String
}
struct Meta : Codable {
let licenseurl : String
}
struct Solarnoon : Codable {
let desc : String
let time : String
let elevation : String
}
struct Sunrise : Codable {
let desc : String
let time : String
}
struct Sunset : Codable {
let time : String
let desc : String
}
You don't really have a SwiftUI class, but that is a different question. I am going to work on fixing getData(). I have tried to comment it extensively, but let me know if you have any questions.
private func getData(from url: String) {
// Personally I like converting the string to a URL to unwrap it and make sure it is valid:
guard let url = URL(string: urlString) else {
print("Bad URL: \(urlString)")
return
}
let config = URLSessionConfiguration.default
// This will hold the request until you have internet
config.waitsForConnectivity = true
URLSession.shared.dataTask(with: url) { data, response, error in
// A check for a bad response
guard let httpResponse = response as? HTTPURLResponse,
httpResponse.statusCode == 200 else {
print("Bad Server Response")
return
}
if let data = data {
// You can print(data) here that will shown you the number of bytes returned for debugging.
//This work needs to be done on the main thread:
DispatchQueue.main.async {
let decoder = JSONDecoder()
if let json = try? decoder.decode(MetDecoder.self, from: data){
print(json)
//At this point, you have your data in a struct
self.sunriseTime = json.dailyData?.solarData?.first?.sunrise?.time
}
}
}
}
.resume()
}
With regard to your structs, you only need them for the data you are trying to parse. If you don't need it, don't worry about it. I would make this a separate class named MetDecoder or something that makes sense to you and indicates the decoder for your JSON. You will also note that I changed the names of some of the variables. You can do that so long as you use a CodingKeys enum to translate your JSON to your struct as in the case of dailyData = "location", etc. This is ugly JSON, and I am not sure why the Met decided everything should be a string, but this decoder is tested and it works:
import Foundation
// MARK: - MetDecoder
struct MetDecoder: Codable {
let dailyData: DailyData?
enum CodingKeys: String, CodingKey {
case dailyData = "location"
}
}
// MARK: - Location
struct DailyData: Codable {
let solarData: [SolarData]?
enum CodingKeys: String, CodingKey {
case solarData = "time"
}
}
// MARK: - Time
struct SolarData: Codable {
let sunrise, sunset: RiseSet?
let solarnoon: Position?
let date: String?
enum CodingKeys: String, CodingKey {
case sunrise, sunset, solarnoon, date
}
}
// MARK: - HighMoon
struct Position: Codable {
let time: String?
let desc, elevation, azimuth: String?
}
// MARK: - Moonrise
struct RiseSet: Codable {
let time: String?
let desc: String?
}
You should see what the National Weather Service does to us in the US to get the JSON. Lastly, when working on JSON I find the following pages VERY helpful:
JSON Formatter & Validator which will help you parse out the wall of text that gets returned in a browser, and
quicktype which will parse JSON into a programming language like Swift. I will warn you that the parsing can give some very ugly structs in Swift, but it gives you a nice start. I used both sites for this answer.
Apple's new framework, Combine, helps to simplify the code needed for async fetch requests. I have used the MetDecoder in #Yrb's response above (you can accept his answer) and altered the getData() function. Just make sure you import Combine at the top.
import Combine
var sunriseTime: String?
var sunsetTime: String?
var solarNoonTime: String?
var solarNoonElevation: String?
func getData() {
let url = URL(string: "https://api.met.no/weatherapi/sunrise/2.0/.json?lat=40.7127&lon=-74.0059&date=2020-12-22&offset=-05:00")!
URLSession.shared.dataTaskPublisher(for: url)
// fetch on background thread
.subscribe(on: DispatchQueue.global(qos: .background))
// recieve response on main thread
.receive(on: DispatchQueue.main)
// ensure there is data
.tryMap { (data, response) in
guard
let httpResponse = response as? HTTPURLResponse,
httpResponse.statusCode == 200 else {
throw URLError(.badServerResponse)
}
return data
}
// decode JSON data to MetDecoder
.decode(type: MetDecoder.self, decoder: JSONDecoder())
// Handle results
.sink { (result) in
// will return success or failure
print("completion: \(result)")
} receiveValue: { (value) in
// if success, will return MetDecoder
// here you can update your view
print("value: \(value)")
if let solarData = value.dailyData?.solarData?.first {
self.sunriseTime = solarData.sunrise?.time
self.sunsetTime = solarData.sunset?.time
self.solarNoonTime = solarData.solarnoon?.time
self.solarNoonElevation = solarData.solarnoon?.elevation
}
}
// After recieving response, the URLSession is no longer needed & we can cancel the publisher
.cancel()
}
from the json data (2nd entry), looks like you need at least:
struct MyTime : Codable {
let solarnoon : Solarnoon?
let sunset : Sunset?
let sunrise : Sunrise?
}
and you need:
var result: MyData?
do {
result = try JSONDecoder().decode(MyData.self, from: data)
}
catch {
print("----> error failed to convert \(error)")
}
I am working with API data that returns JSON data that is hard to decode. The api call is for a batch of stock quotations. When a single quotation (not batch) is called, the result is easily decoded JSON using a simple struct. However, in batch mode the single quote version is grouped within two more levels that I can not decode. In the interest of making this easy to read I will just paste the initial pieces of the data in order to illustrate the issue.
The single quote JSON:
{"symbol":"AAPL","companyName":"Apple Inc.","primaryExchange":"Nasdaq Global Select",
So, that's easy... key, value pairs from the start but in batch mode this becomes:
{"AAPL":{"quote":{"symbol":"AAPL","companyName":"Apple Inc.","primaryExchange":"Nasdaq Global Select",
and then later in that same result would be a second or third or more quote, eg.
}},"FB":{"quote":{"symbol":"FB","companyName":"Facebook Inc.","primaryExchange":"Nasdaq Global Select",
So at the highest level it is not a key but is instead a value. And the second level is a metadata type placeholder for quote (because you can also request other subelement arrays like company, charts, etc.) I can't think of how to handle the outer grouping(s) especially the stock symbols AAPL and FB ... as the outermost elements. Any thoughts anyone?
I have started down the path of JSONSerialization which produces a string that I also cannot get into a usable form.
For this I am using:
let tkrs = "C,DFS"
var components = URLComponents()
components.scheme = "https"
components.host = "api.iextrading.com"
components.path = "/1.0/stock/market/batch"
let queryItemSymbols = URLQueryItem(name: "symbols", value: "\(tkrs)")
let queryItemTypes = URLQueryItem(name: "types", value: "quote")
components.queryItems = [queryItemSymbols,queryItemTypes]
let session = URLSession.shared
let task = session.dataTask(with: components.url!) {(data, response, error) in
guard let data = data else { return }
do {
let json = try JSONSerialization.jsonObject(with: data, options: []) as! [String: Any]
print(json)
which produces:
["C": {
quote = {
avgTotalVolume = 17386485;
calculationPrice = tops;
change = "1.155";
changePercent = "0.0181";
close = "63.8";
closeTime = 1540411451191;
companyName = "Citigroup Inc.";
and there is more data but I'm clipping it short.
The api url's are:
single quote example:
https://api.iextrading.com/1.0/stock/aapl/quote
batch quote example:
https://api.iextrading.com/1.0/stock/market/batch?symbols=aapl,fb&types=quote
The struct I have used successfully for the single quote works nicely with a simple line of code:
let quote = try JSONDecoder().decode(Quote.self,from: data)
where Quote is a struct:
struct Quote: Decodable {
let symbol: String
let companyName: String
let primaryExchange: String
let sector: String
let calculationPrice: String
let open: Double
let openTime: Int
let close: Double
let closeTime: Int
let high: Double
let low: Double
let latestPrice: Double
let latestSource: String
let latestTime: String
let latestUpdate: Int
let latestVolume: Double
let iexRealtimePrice: Double?
let iexRealtimeSize: Double?
let iexLastUpdated: Int?
let delayedPrice: Double
let delayedPriceTime: Int
let extendedPrice: Double
let extendedChange: Double
let extendedChangePercent: Double
let extendedPriceTime: Int
let previousClose: Double
let change: Double
let changePercent: Double
let iexMarketPercent: Double?
let iexVolume: Double?
let avgTotalVolume: Double
let iexBidPrice: Double?
let iexBidSize: Double?
let iexAskPrice: Double?
let iexAskSize: Double?
let marketCap: Double
let peRatio: Double?
let week52High: Double
let week52Low: Double
let ytdChange: Double
}
Edit: based on answer provided
Working in a playground this works well with the batch data:
func getPrices(){
let tkrs = "AAPL,FB,C,DFS,MSFT,ATVI"
var components = URLComponents()
components.scheme = "https"
components.host = "api.iextrading.com" ///1.0/stock/market/batch
components.path = "/1.0/stock/market/batch"
let queryItemSymbols = URLQueryItem(name: "symbols", value: "\(tkrs)")
let queryItemTypes = URLQueryItem(name: "types", value: "quote")
components.queryItems = [queryItemSymbols,queryItemTypes]
let data = try! Data(contentsOf: components.url!)
do {
let response = try JSONDecoder().decode([String:[String: Quote]].self,from: data)
let tickers = ["AAPL","FB","C","DFS","MSFT","ATVI"]
for tk in tickers {
let quote = response[tk]
let price = quote!["quote"]
print("\(price!.symbol) \(price!.latestPrice)")
}
} catch let jsonErr { print("Error decoding json:",jsonErr)}
}
But this solves my initial problem of getting a response back from a URLSession for just a single quote. I can now run through an array of stock symbols and update the latest price for each item with this function.
func getPrice(ticker: String) -> Double {
var price = 0.0
let urlString = "https://api.iextrading.com/1.0/stock/\(ticker)/quote"
let data = try! Data(contentsOf: URL(string: urlString)!)
do {
let response = try JSONDecoder().decode(Quote.self,from: data)
price = response.latestPrice
} catch let jsonErr { print("Error decoding JSON:",jsonErr)}
return price
}
So, I am iterating through an array of open stock trades and setting the price like this...
opentrades[rn].trCurPrice = getPrice(ticker: opentrades[rn].trTicker)
And it works great in my application. Although I am a little worried about how it will workout during times of high latency. I realize I need some error control and will work to integrate that going forward.
Edit/Update: Based on feedback here is the approach I'm taking.
Created a class to be a delegate that accepts an array of open trades and updates the prices.
import Foundation
protocol BatchQuoteManagerDelegate {
func didLoadBatchQuote()
}
class BatchQuoteManager {
var openPositions = [OpenTradeDur]()
var delegate: BatchQuoteManagerDelegate? = nil
func getBatchQuote(tickers: [OpenTradeDur]) {
var tkrs = ""
for tk in tickers {
tkrs = tkrs + "\(tk.trTicker),"
}
var components = URLComponents()
components.scheme = "https"
components.host = "api.iextrading.com"
components.path = "/1.0/stock/market/batch"
let queryItemSymbols = URLQueryItem(name: "symbols", value: "\(tkrs)")
let queryItemTypes = URLQueryItem(name: "types", value: "quote")
components.queryItems = [queryItemSymbols,queryItemTypes]
let session = URLSession.shared
let task = session.dataTask(with: components.url!) {(data,response,error) in
guard let data = data, error == nil else { return }
let response = try! JSONDecoder().decode([String:[String: Quote]].self,from: data)
for i in 0..<tickers.count {
let quote = response[tickers[i].trTicker]
let price = quote!["quote"]
tickers[i].trCurPrice = price!.latestPrice
}
self.openPositions = tickers
if let delegate = self.delegate {
DispatchQueue.main.async {
delegate.didLoadBatchQuote()
}
}
}
task.resume()
}
}
I then extend my ViewController with BatchQuoteManagerDelegate, implement the func didLoadBatchQuote() method where I get the updated prices via the BatchQuoteManager.openPositions array. I just needed to define let batchQuoteManager = BatchQuoteManager() in my ViewController and within viewDidLoad() include the statement batchQuoteManager.delegate = self. Once I know that all the necessary data has been loaded into my ViewController I call the function to get prices (at the end of viewDidLoad()) with batchQuoteManager.getBatchQuote(tickers: opentrades)
And that's it. It is working very nicely so far.
The Dictionary type conditionally conforms to Decodable if its associated KeyType and ValueType conform to Decodable. You can decode the whole Dictionary.
let response = try JSONDecoder().decode([String:[String: Quote]].self,from: data)
let apple = response["AAPL"]
let appleQuote = apple["quote"]
Try this gist in a playground
https://gist.github.com/caquant/eeee66b7b8df447c4ea06b8ab8c1116a
Edit: Here is a quick example with URLSession
let session = URLSession.shared
let dataTask = session.dataTask(with: url) { (data, response, error) in
guard let data = data, error == nil else { return }
let response = try! JSONDecoder().decode([String:[String: Quote]].self,from: data)
let apple = response["FB"]
let appleQuote = apple!["quote"]
print(appleQuote!)
}
dataTask.resume()
Note: The gist was also updated.
I'm calling an API and storing the data in an array.
But if there is no data the debugger says:
Expected to decode Array but found a dictionary instead.
The fail JSON response is:
'{"status":"Failed","msg":"Sorry It\'s Not Working"}'
The success JSON response is:
'[{"id":"509","name":"TEC TEST !"#!12","sortingId":"1"},
{"id":"510","name":"TEC TEST !"#!12","sortingId":"2"},
{"id":"511","name":"TEC TEST !"#!12","sortingId":"3"},
{"id":"512","name":"TEC TEST !"#!12","sortingId":"4"},
{"id":"513","name":"TEC TEST !"#!12","sortingId":"5"},
{"id":"514","name":"TEC TEST !"#!12","sortingId":"6"},
{"id":"519","name":"TEC TEST !"#!12","sortingId":"7"}]'
So I want to switch between fetching my response as
var result:[Items]?
and
var result:Items?
if the Failed JSON gets send
I've been google´ing and searching Stackoverflow without luck
Is there an solution to say if JSON is an array or dictionary?
My Struct:
struct Items: Codable {
let id: String?
let sortingId: String?
let name: String?
let response: String?
let status: String?
let msg: String?
}
My processing of the response:
var result:[Items]?
result = try JSONDecoder().decode([Items].self, from: data!)
DispatchQueue.main.async {
for item in result! {
self.itemArray.append((name: item.name!, id: Int(item.id!)!, sortingId: Int(item.sortingId!)!))
}
}
One solution is to write a custom initializer which conditionally decodes the array or the dictionary.
Please ask the owner of the service to send more consistent JSON. It's very bad. At least the object should be always a dictionary with key status and either the array for key items or the key msg.
This code first tries to decode the array with unkeyedContainer. If it fails it decodes the dictionary.
struct Item: Decodable {
let id: String
let sortingId: String
let name: String
}
struct ItemData : Decodable {
private enum CodingKeys: String, CodingKey { case status, msg }
let status : String?
let msg: String?
var items = [Item]()
init(from decoder: Decoder) throws {
do {
var unkeyedContainer = try decoder.unkeyedContainer()
while !unkeyedContainer.isAtEnd {
items.append(try unkeyedContainer.decode(Item.self))
}
status = nil; msg = nil
} catch DecodingError.typeMismatch {
let container = try decoder.container(keyedBy: CodingKeys.self)
status = try container.decodeIfPresent(String.self, forKey: .status)
msg = try container.decodeIfPresent(String.self, forKey: .msg)
}
}
}
And call it
result = try JSONDecoder().decode(ItemData.self, from: data!)
A – probably more suitable – alternative is to catch the error in the JSONDecoder().decode line and use two simple structs
struct Item: Decodable {
let id: String
let sortingId: String
let name: String
}
struct ErrorData : Decodable {
let status : String
let msg: String
}
and call it
do {
let decoder = JSONDecoder()
do {
let result = try decoder.decode([Item].self, from: data!)
print(result)
} catch DecodingError.typeMismatch {
let result = try decoder.decode(ErrorData.self, from: data!)
print(result)
}
} catch { print(error) }
A big benefit is that all properties can be non-optional.
First of all the JSON does not contain any array. It's very very easy to read JSON. There are only 2 (two!) collection types, array [] and dictionary {}. As you can see there are no square brackets at all in the JSON string.
it will helpful