I am experimenting and I came up with the following challenge: Function A calls a JSON url location from a server Function B is supposed to decode the JSON found at the location identified by Function A.

How can I trigger Function B only when (not if) the Function A has returned a result?

Is it something that AFnetworking would handle? I guess yes, but I was wondering if I am missing something.

Thanks!

I'm not very good with concurrency stuff, but isn't this what the await keyword is for?

https://www.hackingwithswift.com/swift/5.5/async-await

Completion Handlers work well for me. The completion handler on my api client then calls the subsequent functions that consume the json.

Thank you all!!!

@Fly0Strich The async / await is part of the solution, but the trick is that the func that loads the JSON returns before the json parameter is updated.

@Obelix Your guidance and hints did the trick! Code (simplified) of my Model and How I used it as attached for future adventurers!

• An optional URL var
• That calls a function in a Task once var has a value. Note: It didn't work without the Task.
• A call into an async func in the view to update the optional var

@nathanlott I tried your approach, but didn't manage to complete, I guess I was implementing it wrong...

For all below is my Model and the call in the View

Model:

@MainActor class MyModel: ObservableObject {
    @Published var myArray = [ArrayStruct]()
    let storageRef = storage.reference() //Needed for my FirebaseStorage
    //The URL to the JSON to be decoded.
    var jsonUrl: URL? {
        didSet {
            Task {
                await loadData(withUrl: jsonUrl)
            }
        }
    }

    //Get the URL of my JSON, I am using FirebaseStorage
    func getJSONUrl() async {
        storageRef.child("MyJSON.json").downloadURL(completion:  {  url, error in
            guard let url = url, error == nil
            else {
                print(error!.localizedDescription)
                return
            }
            self.jsonUrl = url
        })
    }

    //Load the data into myArray
    func loadData(withUrl: URL?) async  {
        guard let url = withUrl
        else {
            print("Invalid JSON Url")
            return
        }
        do {
            let (data, _) = try await URLSession.shared.data(from: url)
            myArray = try JSONDecoder().decode([ArrayStruct].self, from: data)
        } catch {
            print("Invalid data")
        }
    }
}
struct ArrayStruct: Codable, Identifiable {
    let id: String
    let description: String?
}

Call on the View:

struct ContentView: View {
    @StateObject var myModel = MyModel() //An instance of our Class

    var body: some View {
        Zstack {
            //My view here..
        }
        .task {
            await myModel.getJSONUrl() //Loads the JSON url and subsequent LoadData()
        }
    }
}