How do I map API? - ios

Question

I'm new to swift language and trying to work on the API below..
https://api.foursquare.com/v2/venues/search?ll=40.7484,-73.9857&oauth_token=NPKYZ3WZ1VYMNAZ2FLX1WLECAWSMUVOQZOIDBN53F3LVZBPQ&v=20180616
I'm trying to parse the data and then serialise, however I'm not able to map the data.
struct Venue: Codable {
let id: String
let name: String
let contact: Location
}
struct Location: Codable {
let address: String
let postalCode: String
}
class DataService {
private init() {}
static let shared = DataService()
func getdata() {
guard let url = URL(string: "https://api.foursquare.com/v2/venues/search?ll=40.7484,-73.9857&oauth_token=NPKYZ3WZ1VYMNAZ2FLX1WLECAWSMUVOQZOIDBN53F3LVZBPQ&v=20180616") else { return }
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
if let data = data {
do {
guard let venues = try? JSONDecoder().decode([Venue].self, from: data) else { return }
print(venues[0].id)
} catch let jsonError {
print(jsonError)
}
}
}
task.resume()
}
}
I need to work on venues array ( mainly "id", "name", "location" ( "address", "postalCode" ))
I'm trying to use the codable and decodable, how do I get the the results, please help.

Answer 1

This is a very common mistake.
You ignore the root object (the dictionary containing the meta and response keys). And the venues are in the dictionary for key response, a sub-dictionary of the root object
struct Root : Decodable {
let response : Response
}
struct Response : Decodable {
let venues : [Venue]
}
struct Venue: Decodable {
let id: String
let name: String
let location : Location
}
struct Location: Decodable { // both struct members must be optional
let address: String?
let postalCode: String?
}
And – as Joakim already said in the comments – never ignore Decoding errors. Decoding errors are very descriptive. They contain the specific error message as well as the CodingPath of the error.
let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
if let data = data {
do {
let result = try JSONDecoder().decode(Root.self, from: data)
result.response.venues.forEach{print($0.id)}
} catch {
print(error)
}
}
}
task.resume()