SOLVED: API Call Help

@teamsuperpanda

Sep '20

Hi all,

Longtime listener, first time caller. Finally able to sit down with URLSession.shared.dataTaskPublisher and play around.

Not sure why but I can't get a response from APIs like SpaceX or RickandMorty. Threw various links that worked into Postman and I noticed the ones that don't work open the reponse with '{' where Paul's url user-messages.json opens the reponse with '['

Below is an example of my attempt with the SpaceX API - Latest Launches. Any advise would be great because clearly I'm missing something fundamental.

import SwiftUI
import Combine

struct SpaceX: Codable {
    var flight_number: Int
    var name: String
}

struct ContentView: View {
    @State private var requests = Set<AnyCancellable>()
    @State private var launchesLatest = [SpaceX]()

    var body: some View {
        NavigationView {
            List(launchesLatest, id: \.name) { launches in
                Text(launches.name)
            }
        .navigationBarTitle("SpaceX")
        }
        .onAppear {
            let url = URL(string: "https://api.spacexdata.com/v4/launches/latest")!

            self.fetch(url, defaultValue: [SpaceX]()) {
                self.launchesLatest = $0
            }
        }
    }

    func fetch<T: Decodable>(_ url: URL, defaultValue: T, completion: @escaping (T) -> Void) {

        let decoder = JSONDecoder()

        URLSession.shared.dataTaskPublisher(for: url)
            .retry(1)
            .map(\.data)
            .decode(type: T.self, decoder: decoder)
            .replaceError(with: defaultValue)
            .receive(on: DispatchQueue.main)
            .sink(receiveValue: completion)
            .store(in: &requests)
    }
}

@NigelGee HWS+

Sep '20

Hi @teamsuperpanda,

It because the JSON is not an Array [ ] there forewill only return one value. Add to your struct SpaceX

struct SpaceX: Decodable {
  var flight_number: Int
  var name: String

  static let `default` = SpaceX(flight_number: 0, name: "Unknown")
}

then change the ContentView

@State private var requests = Set<AnyCancellable>()
@State var spaceX: SpaceX

var body: some View {
  NavigationView {
      VStack {
        Text(spaceX.flight_number)
        Text(spaceX.name)
      }
      .navigationBarTitle("SpaceX")
  }
  .onAppear {
      let url = URL(string: "https://api.spacexdata.com/v4/launches/latest")!

      self.fetch(url, defaultValue: SpaceX.default) {
          self.spaceX.name = $0.name
          self.spaceX.flight_number = $0.flight_number
      }
  }
}

and that should return the number and name.

PS you need to add ContentView(spaceX: SpaceX.default) to Previews etc to get rid of errors

@teamsuperpanda

Sep '20

Hey thanks for the help.

Was looking at it and tried different things. I'm at the point where I understand concepts on their own but putting things together is the tricky part.

Appreciate the time.

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