Using alert inside ForEach

[seanmrich]

I have features that use alerts and confirmationDialogs for changes to items in a SwiftUI List. In the past this worked fine because I would attach the dialog modifier to the root of the feature and it would display as a sheet so it didn't matter where in the hierarchy I put it.

List {
  ForEach(store.items) { item in 
    ItemView(item)
      .onTap { send(.itemButtonTapped) }  // Populates destination with dialog state
  }
}
.confirmationDialog(
  $store.scope(state: \.destination?.dialog, action: \.destination.dialog)
)

In iOS 26, though, you need to attach the alert modifier to the row view itself so the popover arrow will point at the view that generated it. This presents a problem because the row elements are inside a ForEach so when you populate the Destination enum it applies to all the rows. The popover attachment point is now indeterminate.

I first solved this with a small piece of state that identifies which row the dialog should apply to:

@Reducer
struct Feature {
  @Reducer
  enum Destination {
    case dialog(ConfirmationDialogState<Feature.Action.Dialog>)
  }
  @ObservableState
  struct State {
    @Presents var destination: Destination.State?
    var items: IdentifiedArrayOf<Item>
    var pendingItem: Item.ID?
  }
  …
}

Then I write a little wrapper to differentiate which row gets the dialog:

extension View {
  @ViewBuilder
  func confirmationDialog(
    for id: Item.ID,
    store: Bindable<StoreOf<Feature>>
  ) -> some View {
    if id == store.wrappedValue.pendingItem {
      self.confirmationDialog(
        store.scope(state: \.destination?.dialog, action: \.destination.dialog)
      )
    } else {
      self
    }
  }
}

Now I can use it in my list of items:

struct FeatureView: View {
  @Bindable var store: StoreOf<Feature>

  var body: some View {
    List {
      ForEach(store.items) { item in 
        ItemView(item)
          .confirmationDialog(for: item.id, store: $store)
      }
    }
  }
}

This works and is a fine fallback, but I then have to repeat this pattern over several features. I'd prefer to just have the dialog state itself keep track of which row it applies to. So I wrote a wrapper that adds an identifier to the dialog state:

struct IdentifiedConfirmationDialogState<Action, ID: Hashable>: Identifiable {
  let id: ID
  var state: ConfirmationDialogState<Action>
}

Now I add a wrapper around the dialog modifier from swift-navigation:

extension View {
  @MainActor
  @ViewBuilder
  public func confirmationDialog<Action, ID>(
    id: ID,
    item: Binding<Store<IdentifiedConfirmationDialogState<Action, ID>, Action>?>
  ) -> some View {
    let conditionalStore = Binding<Store<ConfirmationDialogState<Action>, Action>?>(
      get: {
        guard
          let store = item.wrappedValue,
          store.withState({ $0.id }) == id
        else { return nil }
        return store.scope(state: \.state, action: \.self)
      },
      set: {
        if $0 == nil {
          item.wrappedValue = nil
        }
      }
    )
    self.confirmationDialog(conditionalStore)
  }
}

This compiles, but when I try to use it in my feature we have issues:

@Reducer
enum Destination {
  case dialog(IdentifiedConfirmationDialogState<Feature.Action.Dialog, Item.ID>)
}

In the expansion of the @Reducer macro I get:

'State' is not a member type of generic struct 'IdentifiedConfirmationDialogState<Feature.Action.Dialog, Item.ID>'

Looking at the macro code it looks like the dialog state values are special cased using the _EphemeralState protocol so I added conformance:

extension IdentifiedConfirmationDialogState: _EphemeralState {}

The conformance compiles, but I still get the error when adding it to my Destination enum.

The new design is going to make this pattern more common so I'd like to have a generic approach to solving it. Is there a way to squeeze my little wrapper into a Destination enum and have it work like the standard dialog state?