SWIFT UI request - json

Question

Im trying to make a request on Swift UI in a data file, but nothing is happening on and I seem to not be getting back any data. Im not sure where the issue is, keep in mind I just started swiftUI 2days ago. Any help would be greatly appreciated.
Data Im trying to retrieve.
[
{
"id": 1119,
"make": "Audi",
"model": "100",
"generation": "100 Avant (4A,C4)",
"engine_modification": "2.8 V6 E (174 Hp) quattro Automatic",
"year": 1991,
"powertrain_architecture": "Internal Combustion engine",
"body_type": "Station wagon (estate)",
"number_of_seats": 5,
"number_of_doors": 5,
"urban_fuel_consumption": 13.5,
"extra_urban_fuel_consumption": 8,
"combined_fuel_consumption": 10,
"fuel_type": "Petrol (Gasoline)",
"acceleration": 9.5,
"top_speed": 207,
"power": 174,
"torque": 250,
"engine_location": "Front, Longitudinal",
"engine_displacement": 2771,
"number_of_cylinders": 6,
"position_of_cylinders": "V-engine",
"number_of_valves_per_cylinder": 2,
"fuel_system": "Multi-point indirect injection",
"engine_aspiration": "Naturally aspirated engine",
"kerb_weight": 1550,
"fuel_tank_capacity": 80,
"drive_wheel": "All wheel drive (4x4)",
"number_of_gears": 4,
"front_brakes": "Ventilated discs",
"rear_brakes": "Disc"
},
{
"id": 1120,
"make": "Audi",
"model": "100",
"generation": "100 Avant (4A,C4)",
"engine_modification": "2.8 V6 E (174 Hp) quattro",
"year": 1991,
"powertrain_architecture": "Internal Combustion engine",
"body_type": "Station wagon (estate)",
"number_of_seats": 5,
"number_of_doors": 5,
"urban_fuel_consumption": 13.5,
"extra_urban_fuel_consumption": 8,
"combined_fuel_consumption": 10,
"fuel_type": "Petrol (Gasoline)",
"acceleration": null,
"top_speed": null,
"power": 174,
"torque": 250,
"engine_location": "Front, Longitudinal",
"engine_displacement": 2771,
"number_of_cylinders": 6,
"position_of_cylinders": "V-engine",
"number_of_valves_per_cylinder": 2,
"fuel_system": "Multi-point indirect injection",
"engine_aspiration": "Naturally aspirated engine",
"kerb_weight": 1550,
"fuel_tank_capacity": 80,
"drive_wheel": "All wheel drive (4x4)",
"number_of_gears": 5,
"front_brakes": "Ventilated discs",
"rear_brakes": "Disc"
},
Code for request
import SwiftUI
import Foundation
struct astonMartin: Decodable, Identifiable{
let id: Int
var make: String
var model: String
var generation: String
var engine_modification: String
var year: Int
var powertrain_architecture: String
var body_type: String
var number_of_seats: Int
var number_of_doors: Int
var urban_fuel_consumption: Int
var extra_urban_fuel_consumption: Int
var combined_fuel_consumption: Int
var fuel_type: String
var acceleration: Int
var top_speed: Int
var power: Int
var torque: Int
var engine_location: String
var engine_displacement: Int
var number_of_cylinders: Int
var position_of_cylinders: String
var number_of_valves_per_cylinder: Int
var fuel_system: String
var engine_aspiration: String
var kerb_weight: Int
var fuel_tank_capacity: Int
var drive_wheel: String
var number_of_gears: Int
var front_brakes: String
var rear_brakes: String
}
class secondaryCall: ObservableObject {
#Published var cars: [astonMartin] = []
func getCars() {
guard let url = URL(string: "URL INSERTED HERE") else { fatalError("Missing URL") }
let urlRequest = URLRequest(url: url)
let dataTask = URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in
if let error = error {
print("Request error: ", error)
return
}
guard let response = response as? HTTPURLResponse else { return }
if response.statusCode == 200 {
guard let data = data else { return }
DispatchQueue.main.async {
do {
let decodedCars = try JSONDecoder().decode([astonMartin].self, from: data)
self.cars = decodedCars
} catch let error {
print("Error decoding: ", error)
}
}
}
}
dataTask.resume()
}
}
content view
import SwiftUI
struct ContentView: View {
#State var isLinkActive = false
#EnvironmentObject var allCars: secondaryCall
var body: some View {
NavigationView{
ZStack{
Image("car")
.resizable()
.scaledToFill()
.ignoresSafeArea(.all)
.overlay(
Rectangle()
.opacity(0.6)
.ignoresSafeArea(.all)
)
NavigationLink(destination: HomeView()) {
Text("Click to view all cars")
.foregroundColor(.white)
}
.padding()
.background(.orange)
.clipShape(Capsule()
)
}
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
.environmentObject(secondaryCall())
}
}
Home view:
//
// HomeView.swift
// project
//
//
import SwiftUI
struct HomeView: View {
#EnvironmentObject var allCars: secondaryCall
var body: some View {
ScrollView{
Text("All cars for Aston Martin")
.bold()
.textCase(.uppercase)
.font(.headline)
ForEach(allCars.cars){car in
HStack(alignment: .top){
Text("\(car.make)")
}
}
}
.onAppear{
allCars.getCars()
}
}
}
struct HomeView_Previews: PreviewProvider {
static var previews: some View {
HomeView()
.environmentObject(secondaryCall())
}
}
Project App
//
// projectApp.swift
// project
//
//
import SwiftUI
#main
struct projectApp: App {
var allCars = secondaryCall()
var body: some Scene {
WindowGroup {
SplashView()
.environmentObject(allCars)
}
}
}

Answer 1

Form your data, I see that the reason you not getting data is that because you construct some variables in struct astonMartin with wrong type compare to the JSON you given.
Given you some example
In Json: "urban_fuel_consumption": 13.5, which should be Double but in struct astonMartin you set is Int
In Json: "acceleration": null, which should be Double? because it is nil here but in struct astonMartin you set is Double
In Json: "top_speed": null, which should be Int? because it is nil here but in struct astonMartin you set is Int
And maybe more of that ...
You should recheck each type of variables in your struct
Code will change like follow
struct astonMartin: Decodable, Identifiable {
let id: Int
var make: String
var model: String
var generation: String
var engine_modification: String
var year: Int
var powertrain_architecture: String
var body_type: String
var number_of_seats: Int
var number_of_doors: Int
var urban_fuel_consumption: Double // was Int
var extra_urban_fuel_consumption: Int
var combined_fuel_consumption: Int
var fuel_type: String
var acceleration: Double? // was Int
var top_speed: Int? // was Int
var power: Int
var torque: Int
var engine_location: String
var engine_displacement: Int
var number_of_cylinders: Int
var position_of_cylinders: String
var number_of_valves_per_cylinder: Int
var fuel_system: String
var engine_aspiration: String
var kerb_weight: Int
var fuel_tank_capacity: Int
var drive_wheel: String
var number_of_gears: Int
var front_brakes: String
var rear_brakes: String
}
More over, when you parse json not right it prints error in debug mode because you currently catch error there. Make sure you notice that.