SwiftUI List can't add index to alternate background colors

Question

How to implement alternate list background colors in my SwiftUI lists to display system colors or custom colors.

import SwiftUI

struct FriendshipListView: View {
    
    @EnvironmentObject var listViewModel: MenuListFriendshipViewModel
    
    var body: some View {
        NavigationView {
            List {
                //Use the $ syntax to pass a binding on to the subviews
                ForEach($listViewModel.items) { $item in
                    MenuListRowView(item: $item)
                }
            }
            .navigationBarTitle(Text("Friendships / Relationships"))
            .listStyle(PlainListStyle())
        }
    }
}

struct ListView_Previews: PreviewProvider {
    static var previews: some View {
        FriendshipListView()
        .environmentObject(MenuListFriendshipViewModel())
    }
}

I was trying to implement this code snippet but just don't understand how to apply [index] to my ForEach loop.

List {
    ForEach(items.indices) { index in
        Text(items[index])
            .listRowBackground((index  % 2 == 0) ? Color(.systemBlue) : Color(.white))
    }
}

have you seen stackoverflow.com/questions/59295206/… ?

Jacob Lange
– Jacob Lange

2022-10-06 01:31:26 +00:00
Commented Oct 6, 2022 at 1:31 — Jacob Lange
– Jacob Lange, Commented Oct 6, 2022 at 1:31

workingdog support Ukraine · Accepted Answer · 2022-10-06 02:56:27Z

1

in your particular case, with the binding required, try this approach, works for me:

ForEach($listViewModel.items) { $item in
    let index = listViewModel.items.firstIndex(where: {$0.id == item.id})
    MenuListRowView(item: $item)
        .listRowBackground(((index ?? 0) % 2 == 0) ? Color.blue : Color.red)
}

edited Oct 6, 2022 at 2:56

answered Oct 6, 2022 at 2:24

workingdog support Ukraine

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Comments

LIN SUNG HAO · Accepted Answer · 2022-10-06 02:07:13Z

1

It's the same way as the code snippet. Set listRowBackground under the MenuListRowView(item: $item)

MenuListRowView(item: $item)
    .listRowBackground(Color.green)

answered Oct 6, 2022 at 2:07

LIN SUNG HAO

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