ListCellSizingFlicker

ListCellSizingFlicker.swift

import SwiftUI

struct Item: Identifiable {
  let id = UUID()
  let title = "Hello"
}

let items = [
  Item(),  Item(),  Item(),  Item(),  Item(),  Item(),  Item(),  Item(),  Item(),  Item(),  Item(),
  Item(),  Item(),  Item(),  Item(),  Item(),  Item(),  Item(),
]

struct ContentView: View {
  
  @State private var animated = true
  
  var body: some View {
    NavigationStack {
      Toggle("Animated", isOn: $animated).padding()
      
      List {
        ForEach(items) { item in
          Cell(item: item, animated: animated)
        }
      }
    }
  }
  
  struct Cell : View {
    
    @State private var isExpanded = false
    
    let item     : Item
    let animated : Bool
    
    private func toggle() {
      if animated {
        withAnimation { isExpanded.toggle() }
      }
      else {
        isExpanded.toggle()
      }
    }
    
    var body: some View {
      Label {
        VStack {
          HStack {
            Text(verbatim: item.title)
            Spacer()
            Image(systemName: "battery.75percent")
          }
          .contentShape(Rectangle())
          .onTapGesture(perform: toggle)
          
          if isExpanded {
            VStack {
              Text("More")
              Text("Info")
              Text("on item")
            }
          }
        }
      } icon: {
        Image(systemName: "lightswitch.on.square")
      }
    }
  }
  
}

#Preview {
    ContentView()
}

Wow this is embarrassing for the SwiftUI team. Quite ugly. I couldn't figure out a way to make it look substantially better :-/

I wouldn't call it embarrassing, it seems like a deficiency that should be addressed and it is sad that it still exists. I would even be OK to disable the slide out animation, but the offset issue is really bad.

One thing that can be done to make it work is to put the expanded content into own rows. But that has a lot of other side effects that just don't work well in my particular scenario.

Context: I do have an (4y?) old SwiftUI app in which I had to drop List originally because of such issues. I'm working on an update and thought I'd give List another try. Looks like I have to stick to a plain ScrollView even though I'd love to use the List for the extra features.