SwiftUI table with default styles crashes (macOS) (Could not cast value of type 'SwiftUI.ListCoreCellHost')

Using Swift
1

I am trying to implement a table that follows system style on macOS. There seem to be two ways to do this:

struct MyRow: Identifiable {
    let id = UUID()
    var title: String
}


struct MySection: Identifiable {
    let id = UUID()
    var title: String
    var rows: [MyRow]
}

  1. Iterate via List:

     List(sections) { section in
     Section(header: Text(section.title)) {
         ForEach(section.rows) { row in
             Text(row.title)
         }
     }
 }

This works and is stable, but does not apply any formatting. It seems to use stacks under the hood:
(can't include screenshot, restricted by forum)

  1. Iterate via ForEach

     List {
     ForEach(sections) { section in
         Section(header: Text(section.title)) {
             ForEach(section.rows) { row in
                 Text(row.title)
             }
         }
     }
 }

This is exactly what I want. For some reason, this applies the system styles, has floating group rows etc. - all the things you would expect from a native NSTableView:

Screen Shot 2020-07-05 at 11.51.07

But here is the problem:
It crashes as soon as the order of sections/rows changes at a later point. I assume this is a SwiftUI Bug:

**Could not cast value of type 'SwiftUI.ListCoreCellHost' (0x7fff87be7580) to 'SwiftUI.ListCoreHeaderHost' (0x7fff87be75f8).**

**2020-07-05 11:52:00.779004-0700 SwiftUIRepro[47587:1158522] Could not cast value of type 'SwiftUI.ListCoreCellHost' (0x7fff87be7580) to 'SwiftUI.ListCoreHeaderHost' (0x7fff87be75f8).**

I created a repro to demonstrate the bug here: GitHub - paxos/SwiftUICrashRepro

Also, on macOS 11.16 this doesn't work at all; it just shows empty rows. I assume we are supposed to use the new outline views in the future?

I am bit stuck here. I could use approach 1) and just style everything by myself, but that is usually not what you want to do on macOS.

Any ideas? Am I doing something wrong here?

2

You should report this bug to Apple.

3

I sent it as feedback #7854652 - do you know any other ways to do it?

4

No, that’s all you can do.

5

I'm actually running into this SAME exact error trying to do the same exact thing. Nesting Lists. I did find that actually wrapping the second ForEach in a List actually prevented that error from occurring but the functionality is a bit different. I literally just found this out so still working on seeing if I can get the same look with actual nested Lists

6

Okay so I found that wrapping the second ForEach in a VStack actually does the trick.