SOLVED: URLSession and LoadingView

@Kdkwn

Mar '23

Hey,

i created a simple method to fetch products from a API:

class ViewModel: ObservableObject {

    @Published var product: Product?
    @Published var isErrorAppearing: Bool = false
    @Published var errorMessage: String = ""
    @Published var isLoading: Bool = false

    func getProductByBarCode(barcode: String) async {
        DispatchQueue.main.async {
            self.isLoading = true
        }

        guard let url = URL(string: "") else {
            self.isErrorAppearing = true
            self.errorMessage = ""
            return
        }

        do {
            let (data, _) = try await URLSession.shared.data(from: url)
            let decoded = try JSONDecoder().decode(CompleteProduct.self, from: data)

            DispatchQueue.main.async {
                self.product = decoded.product
                self.isLoading = false
            }
        } catch {
            DispatchQueue.main.async {
                self.isErrorAppearing = true
                self.errorMessage = ""
            }
        }
    }
}

My problem is now, I created this inside a view model, and publish the product when I get it from the API.

I am relativ new to Swift and have some questions to this.

How I can create a LoadingView when I call the Method to fetch the products? I want to have a custom LoadingView thst appears when a buttons get pressed in the HomeView as long the data has appers I want to switch the View from the LoadingView to another View, where the data is displayed.
Next question is, how can I handle the errors better or is that a good way how I did that here?

Thank you really much for your help!

@NigelGee HWS+

Mar '23

Couple of things Let the View handle which Loading to do based on the data. So ViewModel is this

class ViewModel: ObservableObject {
    @Published var product: Product?
    @Published var showingAlert: Bool = false
    @Published var errorMessage: String = ""

    func getProductByBarCode(barcode: String) async {
        guard let url = URL(string: barcode) else {
            showingAlert = true
            errorMessage = "Unable to get URL"
            return
        }

        do {
            let (data, _) = try await URLSession.shared.data(from: url)
            let decoded = try JSONDecoder().decode(CompleteProduct.self, from: data)

            product = decoded.product
        } catch {
            showingAlert = true
            errorMessage = "Unable to decode data!"
        }
    }
}

and the View

struct ContentView: View {
    @StateObject var viewModel = ViewModel()
    let barCode = "Some URL"

    var body: some View {
        VStack {
            if let product = viewModel.product { // will only show when it has data
                Text(product.name)
            } else {
                ProgressView() // Used built in loading view but you can make your own
            }
        }
        .padding()
        .alert("Error", isPresented: $viewModel.showingAlert) { } message: { Text(viewModel.errorMessage) }
        .task { await viewModel.getProductByBarCode(barcode: barCode) }
    }
}

PS just used simple structs for the model

struct Product: Identifiable, Codable {
    var id = UUID()
    var name: String
}

struct CompleteProduct: Codable {
    let product: Product
}

@Kdkwn

Mar '23

Thank you very much! :)

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