如何从 Swift 中的视图访问 model 中的变量

Question

So I finally have the isoCountrycode from the user's current location and need to concatenate it on the end of an API url in order that the URL will respond with the relevant information.

The location's isoCountrycode is found in model/LocationViewModel.swift

Code:

import Foundation
import Combine
import CoreLocation

class LocationViewModel: NSObject, ObservableObject{
  
  @Published var userLatitude: Double = 0
  @Published var userLongitude: Double = 0
  
  private let locationManager = CLLocationManager()
  
  override init() {
    super.init()
    self.locationManager.delegate = self
    self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
    self.locationManager.requestWhenInUseAuthorization()
    self.locationManager.startUpdatingLocation()
  }
}

extension LocationViewModel: CLLocationManagerDelegate {
  
  func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    guard let location = locations.last else { return }
    userLatitude = location.coordinate.latitude
    userLongitude = location.coordinate.longitude
    print(location)
    
    CLGeocoder().reverseGeocodeLocation(location) { (placemark, error) in
        if error != nil
        {
            print("there is an error")
        }
        else
        {
            if let place = placemark?[0]
            {
                let countrycode = place.isoCountryCode
            }
        }
    }
    
  }
}

And the view where I need to use it is here (located in views/HomeAPIContentView.swift), where I would add it to the end of the API URL.eg "https://emergency-phone-numbers.herokuapp.com/country/" + countrycode

Code for view file is here:

import SwiftUI

struct Response: Decodable {
    var content: [Result]
}

struct Result : Decodable {
    var code: String
    var fire: String
    var name: String
    var police: String
    var medical: String
}

struct HomeAPIContentView: View {
    @State private var content = [Result]()
    @ObservedObject var locationViewModel = LocationViewModel()

    var body: some View {
        List(content, id: \.code) { item in
            VStack(alignment: .center) {
                Text("Latitude: \(locationViewModel.userLatitude)")
                Text("Longitude: \(locationViewModel.userLongitude)")
                Text(item.name)
                    .font(.headline)
                HStack {
                    Text("Medical:")
                    Text(item.medical)
                        .foregroundColor(Color.red)
                    Text("Police:")
                    Text(item.police)
                        .foregroundColor(Color.red)
                    Text("Fire:")
                    Text(item.fire)
                        .foregroundColor(Color.red)
                }
            }
        }
        .onAppear(perform: loadData)
    }
    func loadData() {
        
        let url = URL(string: "https://emergency-phone-numbers.herokuapp.com/country/us")!

        URLSession.shared.dataTask(with: url) { data, response, error in
            if let error = error { print(error); return }
            do {
                let decodedResponse = try JSONDecoder().decode(Result.self, from: data!)
                // we have good data – go back to the main thread
                DispatchQueue.main.async {
                    // update our UI
                    self.content = [decodedResponse]
                }
                
            } catch {
                print(error)
            }
        }.resume()
        
    }
}

If I could access the cc variable from the view, it sounds like an easy enough thing to do but I have no idea how to do that. Please advise.

Thanks in advance.

Answer 1

You have a log way to go but here is some help

import Foundation
import Combine
import CoreLocation

class LocationViewModel: NSObject, ObservableObject{
    //MARK: Properties
    @Published var content = [MyResult]()
    @Published var userLatitude: Double = 0
    @Published var userLongitude: Double = 0
    @Published var isoCountryCode = ""{
        didSet{
            //load the data once you have a countrycode
            loadData()
        }
    }
    
    private let locationManager = CLLocationManager()
    //MARK: init
    override init() {
        super.init()
        self.locationManager.delegate = self
        self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
        self.locationManager.requestWhenInUseAuthorization()
        self.locationManager.requestLocation()
    }
    //MARK: Functions
    func loadData() {
        
        let url = URL(string: "https://emergency-phone-numbers.herokuapp.com/country/\(isoCountryCode)")!
        
        URLSession.shared.dataTask(with: url) { data, response, error in
            if let error = error { print(error); return }
            do {
                let decodedResponse = try JSONDecoder().decode(MyResult.self, from: data!)
                // we have good data – go back to the main thread
                DispatchQueue.main.async {
                    // update our UI
                    self.content = [decodedResponse]
                }
                
            } catch {
                print(error)
            }
        }.resume()
        
    }
}

extension LocationViewModel: CLLocationManagerDelegate {
    
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        guard let location = locations.last else { return }
        userLatitude = location.coordinate.latitude
        userLongitude = location.coordinate.longitude
        print(location)
        
        CLGeocoder().reverseGeocodeLocation(location) { (placemark, error) in
            if error != nil
            {
                print("there is an error \(error)")
            }
            else
            {
                if let place = placemark?[0]
                {
                    self.isoCountryCode = place.isoCountryCode ?? ""
                }
            }
        }
        
    }
    //You have to respond to errors
    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
        print(error)
    }
    //You have to respond to changes in autorization too
    func locationManagerDidChangeAuthorization(_ manager: CLLocationManager) {
        
    }
}

import SwiftUI

struct Response: Decodable {
    var content: [MyResult]
}
//Result already exists in Swift you will cause issues if you use names that are already used
struct MyResult : Decodable {
    var code: String
    var fire: String
    var name: String
    var police: String
    var medical: String
}

struct HomeAPIContentView: View {
    
    @StateObject var locationViewModel = LocationViewModel()
    
    var body: some View {
        List(locationViewModel.content, id: \.code) { item in
            VStack(alignment: .center) {
                Text("Latitude: \(locationViewModel.userLatitude)")
                Text("Longitude: \(locationViewModel.userLongitude)")
                Text(item.name)
                    .font(.headline)
                HStack {
                    Text("Medical:")
                    Text(item.medical)
                        .foregroundColor(Color.red)
                    Text("Police:")
                    Text(item.police)
                        .foregroundColor(Color.red)
                    Text("Fire:")
                    Text(item.fire)
                        .foregroundColor(Color.red)
                }
            }
        }
        
    }
    
}