Parse JSON Data

App Development
1

Hi guys,

since me Firebase works great I need one last step and that’s some JSON Data I have to parse.

I have a JSON which looks like this (“weights” with objects in it) and I need to display every single value of the array Items on its own. It’s hard because there are only tutorials for ListView etc. But I need single variables to display in ContentView.

I got stuck how I have to send the variables from “JSONManager” to “ContentView”

Bildschirm­foto 2023-03-13 um 20.13.05
Bildschirm­foto 2023-03-13 um 20.13.05764×962 63.9 KB

Items.swift look like this:

import Foundation

struct Weights: Codable {

let weights : [Items]

}

struct Items: Codable {

let oew: String

let pax_count: String

let bag_count: String
}

My JSONManager looks like this:

import Foundation

class JSONManager: ObservableObject {
@Published var weights : [Items]

init() {
    fetchRemoteData()
}


func fetchRemoteData() {
    let urlString = "https://www.simbrief.com/api/xml.fetcher.php?username=alancord&json=1"

    let url = URL(string: urlString)
    let defaultSession = URLSession(configuration: .default)
    let dataTask = defaultSession.dataTask(with: url!) { data, response, error in

        if error != nil {
            print(error!.localizedDescription)
            return
        }

        do {
            let json = try JSONDecoder().decode(Weights.self, from: data!)
            DispatchQueue.main.async {
                self.weights = json.weights
            }
        } catch {
            print(error.localizedDescription)
        }
    }
    dataTask.resume()
}

}

ContentView looks like this:

import SwiftUI

struct ContentView: View {

var body: some View {
   
    VStack {
        
        Text("\(oew)")
        Text("\(pax_count)")
        Text("\(bag_count)")
    }
}

}

struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}

2

Add a @StateObject property for the JSON Manager to the content view.

@StateObject var jsonData: JSONManager

The @StateObject property has the items you want to display.

1 Like
3

Thank you. I added it. You are right it is mandatory when I have a @Published Variable I need @StateObject somewhere else. Unfortunately I have many more errors…

import SwiftUI

struct ContentView: View {

@StateObject var jsonData: JSONManager

var body: some View {
   
    VStack {
        
        Text("\(jsonData.weights)")
       
    }
}

}

struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView(jsonData: [Items])
}
}

4

You are going to need a ForEach block to go through the items and create a view for each item. The code will look similar to the following:

var body: some View {
   
    VStack {
        ForEach(jsonData.weights, id: \.self) { weight in
            Text(weight.oew)
            Text(weight.pax_count)
            Text(weight.bag_count)
        }
    }
}

You’re also going to have to call the fetchRemoteData function to get data to show in the view. The most common way to do this is to add a .task modifier to the view and make the call there.

1 Like
5

Thank you for the hint - do you know what I have to put in the Preview Part ?

struct ContentView_Previews: PreviewProvider {

static var previews: some View {

ContentView(jsonData.content(Items)). // does not work Cannot find ‘jsonData’ in scope

}

}

6

You have to supply an instance of JSONManager as the jsonData argument for the content view in the preview.

ContentView(jsonData: JSONManager())

You might have to supply a weights argument when calling the JSONManager constructor.

You may also consider commenting out the preview part if you keep getting build errors because of an error in the preview code.

1 Like