I'm running into a problem I can't explain where modifiying elements of a list after deletions leads to a crash. First here's an example which doesn't crash to illustrate the setup:

import SwiftUI

struct TestItem: Identifiable {

    let id = UUID()

    var name = ""
    var quantity = 1

    init(_ name: String = "") {
        self.name = name
    }
}

class TestList: ObservableObject {

    var id: UUID = UUID()
    @Published var items: [TestItem]

    init() {
        self.items = [
            TestItem("Apples"),
            TestItem("Oranges"),
            TestItem("Bananas"),
        ]
    }
}

struct TestingView: View {

    @StateObject var list = TestList()

    var body: some View {
        List() {
            ForEach($list.items, editActions: .all) { $item in
                TestingDetailView(item: $item)
            }
        }
    }
}

struct TestingDetailView: View {

    @Binding var item: TestItem

    var body: some View {
        Button(action: {item.quantity += 1}) {
            HStack {
                Text(item.name)                
                Spacer()
                Text("\(item.quantity)")
            }
        }
    }
}

Here, tapping on a row causes the corresponding quantity to increase, and in particular this continue to work without any crashes even after deleting some elements of the list. Now, suppose that instead of using a Button to trigger this change, I instead trigger the change when the user interacts with a TextField using onEditingChanged:

struct TestingDetailView2: View {

    @Binding var item: TestItem

    @State private var input = ""

    func increaseQuantity(editing: Bool) {
        if !editing {
            item.quantity += 1
        }
    }

    var body: some View {
        HStack {
            Text(item.name)
            TextField("Type anything...", text: $input, onEditingChanged: increaseQuantity)
            Spacer()
            Text("\(item.quantity)")
        }
    }
}

At first glance all seems fine, but if I first delete the second entry ('Oranges') of the list and then submit something to the remaining 'Bananas' text field, the app crashes consistently. Naturally this is a simplified example, and there are some workarounds here such as using .onSubmit instead. However I'm keen to use onEditingChanged in the app I'm working on, so if anyone can explain what's going on here I'd be hugely grateful!

I'm running Xcode 14.3.1.

Thanks in advance!

Try replacing the ForEach with this. (I'm still on MacOS 12 so I cannot test it.)

ForEach($list.items, editActions: .all) { element in
    if let idx = list.items.firstIndex(where: {$0.id==element.id}), idx < list.items.count {
        TestingDetailView(item: element)
    }
}

Thank you both for the insightful replies, with your help I've managed to fix the issue!