SwiftUI MVVM how to iterate and get index of array

Question

My project is creating an ordering app, and in this screen about the menu detail, there are menu variants which users can choose / add-on, I need to iterate an array of [MenuDetailVariantGroup] and I need to get the index of the array, how do I do this? While in the for loop I also need to append a variable into a @Published var variantChosen, however if I do self.viewModel.variantChosen.append(1), it always returns an error. Below is my codes:

MenuDetailData.swift

struct MenuDetailData: Codable, Identifiable {
    let id = UUID()
    let idMenu: String
    let menuName: String
    let variantGroup: [MenuDetailVariantGroup]
}

MenuDetailVariantGroup.swift

struct MenuDetailVariantGroup: Codable, Identifiable, Hashable {
    let id = UUID()
    let variantGroupName: String
    let variant: [MenuDetailVariant]
    let limit: Int
}

MenuDetailVariant.swift

struct MenuDetailVariant: Codable, Identifiable, Hashable {
    let id = UUID()
    let variantName: String
}

MenuDetailViewModel.swift

class MenuDetailViewModel: ObservableObject, MenuDetailService {
    var apiSession: APIService
    @Published var detaildata: MenuDetailData?
    @Published var variantGroup = [MenuDetailVariantGroup]()
    @Published var variantChosen: Array<Int> = []
    
    var cancellables = Set<AnyCancellable>()
    
    init(apiSession: APIService = APISession()) {
        self.apiSession = apiSession
    }
    
    func getMenuDetail() {
        let cancellable = self.getMenuDetail()
            .sink(receiveCompletion: { result in
                switch result {
                case .failure(let error):
                    print("Handle error: \(error)")
                case .finished:
                    break
                }
                
            }) { (detail) in
                self.detaildata = detail.data
                self.variantGroup = detail.data.variantGroup
        }
        cancellables.insert(cancellable)
    }
    
}

MenuDetailView

struct MenuDetailView: View {
    @ObservedObject var viewModel = MenuDetailViewModel()
    
    var body: some View {
        ForEach(self.viewModel.variantGroup, id: \.self) { vg in
                /*** I Need to get the index of each iteration here, how? ***/
                VStack {
                    HStack {
                        Text(vg.variantGroupName)
                        Text(String(self.viewModel.arrVariantChoosen[0]))
                    }
                    VStack {
                        ForEach(vg.variant, id: \.self) { v in
                            Text(v.variantName)
                        }
                    }
                }
                // I also need to append Int to @Published var variantChosen
                self.viewModel.variantChosen.append(1)
                // This always return error:
                // Type '()' cannot conform to 'View'; only struct/enum/class types can conform to protocols
            }
        }
    }
}

This is the codes that I have tried so far but failed and return empty

// This returns blank
ForEach(0..<self.viewModel.variantGroup.count) { i in
    Text("\(self.viewModel.variantGroup[i].variantGroupName)")
}

// This too returns blank
ForEach(self.viewModel.variantGroup.indices) { i in
    Text("\(self.viewModel.variantGroup[i].variantGroupName)")
}

Thank you all in advance

What you have tried should work fine, see [this answer](https://stackoverflow.com/a/57244880/9223839) for instance. Maybe the array is empty? You have a method `getMenuDetail` in your view model but is it ever called? — Joakim Danielson, Jan 12 '21 at 12:24
It does get called, with the current "ForEach(self.viewModel.variantGroup, id: \.self) { vg in" returns the data, but I could not get the index, weirdly with the "ForEach(0.. — Charas, Jan 12 '21 at 12:26
Also why is that method calling itself? But maybe you should ignore that function for now and hardcode some values into the `variantGroup` array and see if you can get the `ForEach` to work, that way you deal with one problem at a time. — Joakim Danielson, Jan 12 '21 at 12:30

score 3 · Accepted Answer · answered Jan 12 '21 at 12:34

3

You can use enumerated to have both index and element, like

    var body: some View {
        ForEach(Array(self.viewModel.variantGroup.enumerated()), id: \.1) { index, vg in
                /*** I Need to get the index of each iteration here, how? ***/
                VStack {

answered Jan 12 '21 at 12:34

Asperi

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Thanks you so much man, this does work, how do I append the value to the array in the ViewModel @Published var variantChosen in the foreach loop though? – Charas Jan 12 '21 at 12:46

SwiftUI MVVM how to iterate and get index of array

1 Answers1