Passing data from API Call to UI

App Development
1

Hi,
API call request runs fine as print command within API call shows correct data has been downloaded.
Data in API has been made Observable and @Published, and Observed in UI, but receive two errors attempting to show data in UI: “Cannot convert value of type ‘DataModel?’ to expected argument type ‘Range’” and “Initializer ‘init(_:)’ requires that ‘Binding’ conform to ‘StringProtocol’”.
Here is code within UI:

   
   @ObservedObject var apiCall = APICall()
   
   var body: some View {
       //        Text("Hello World")
       List(apiCall.dataPull) {
           data in
           Text($apiCall.byCountry[28].cntry)
       }
   }

And here is API Call:

class APICall : ObservableObject, Identifiable {
   
   @Published var dataPull: DataModel? = nil
   
   init() {
       let urlCall = URL(string: "https://api.covid19api.com/summary")
       guard urlCall != nil else {
           print("Error reaching API")
           return
       }
       let session = URLSession.shared
       let dataTask = session.dataTask(with: urlCall!) { (data, response, error) in
           if error == nil && data != nil {
               let decoder = JSONDecoder()
               do {
                   let dataPull = try decoder.decode(DataModel.self, from: data!)
                   print(dataPull.byCountry[37].cntry)
               }
               catch {
                   print("Server busy, try again in 5 min.")
               }
               DispatchQueue.main.async {
                   self.dataPull = self.dataPull
               }
           }
       }
       dataTask.resume()
   }
}

Any suggestions?

2

what is your DataModel?

it seems you are trying to save self.dataPull to itself. try changing your variable names to avoid confusion and conflict

3

Hi Francis,
Thanks for response. I’m sure you’re on the right track, as I’m a beginner and somewhat clueless & confused as to how to declare the model, vs. a variable and when to us a colon “:” to assign a data model to variable, vs an equal sign “=”. Why sometimes one and sometimes the other??

In any case, here’s what the DataModel looks like:

import Foundation

class DataModel: Decodable, Identifiable {
    let global: Global
    let byCountry: [ByCountry]
    let date: String
    
    enum CodingKeys: String, CodingKey {
        case global = "Global"
        case byCountry = "Countries"
        case date = "Date"
    }
    
    struct Global: Decodable {
        let globalNC: Int
        let globalTC: Int
        let globalND: Int
        let globalTD: Int
        let globalNR: Int
        let globalTR: Int
        
        enum CodingKeys: String, CodingKey {
            case globalNC = "NewConfirmed"
            case globalTC = "TotalConfirmed"
            case globalND = "NewDeaths"
            case globalTD = "TotalDeaths"
            case globalNR = "NewRecovered"
            case globalTR = "TotalRecovered"
        }
    }
    
    struct ByCountry: Decodable {
        let cntry: String
        let ccode: String
        let slug: String
        let cntryNC: Int
        let cntryTC: Int
        let cntryND: Int
        let cntryTD: Int
        let cntryNR: Int
        let cntryTR: Int
        let date: String
        
        enum CodingKeys: String, CodingKey {
            case cntry = "Country"
            case ccode = "CountryCode"
            case slug = "Slug"
            case cntryNC = "NewConfirmed"
            case cntryTC = "TotalConfirmed"
            case cntryND = "NewDeaths"
            case cntryTD = "TotalDeaths"
            case cntryNR = "NewRecovered"
            case cntryTR = "TotalRecovered"
            case date = "Date"
        }
    }
}

And I will take your advice and rename some of the objects to avoid confusion. Thanks.

FYI, I have been playing with code non-stop to try and fix things, basically simplifying code down to where I could hopefully de-bug it. Here is latest I have:

struct ContentView: View {
    
    @State @ObservedObject var apiCall = APICall()
    
    var body: some View {
        
        NavigationView {
            List {
                VStack {
 //                   Text("Hello Dummy")
 //                   Text("Hello Dummy2")
                    Text(String(apilCall.byCountry[40].cntryNC))
                }
            }
            .navigationBarTitle("COVID Dashboard")
        }
        .onAppear {
            self.apiCall.pullData()
        }

For the above, if I just use the 2 Text statements that are commented out, things are fine.

When I uncomment the Text statement trying to display the apiCall data, I get this error behind it: Use of unresolved identifier 'apilCall'.

Also, I know that declaring the single item from byCountry will only show that one item. I understand that, but have again tried to simply everything to just be able to display a data point, before jumping into a ForEach statement or range, etc…

I know these are stupid questions but again I’m just learning and am totally confused by the model, vs. use of : , vs. use of =, etc…

Really appreciate your help.

– Doxie

4

well you made a spelling mistake, it should be apiCall not apilCall

i also think you are just making it hard for yourself to make use of the API call. it seems it returns a JSON file. so i suggest using SwiftyJSON instead of the “DataModel” that you created

check out our article for it

5

Thanks, Francis… will check it out.