Crash when array is empty in iOS 14.3

Question

I'm trying to show some placeholder data when the array is empty. This works in iOS 13.7 but something has changed in iOS 14.3 so when the last item is deleted you get this crash:

Fatal error: Index out of range: file Swift/ContiguousArrayBuffer.swift, line 444

If I comment out testStore.data.isEmpty and just return the Form I get no crash.

How can I show placeholder when array is empty in iOS 14.3?

struct Test: Identifiable {
    var text: String
    var id: String { text }
}

extension Test {
    final class Store: ObservableObject {
        @Published var data = [Test(text: "Hi"), Test(text: "Bye")]
    }
}

struct TestList: View {
    
    @EnvironmentObject var testStore: Test.Store
    
    var body: some View {
        Group {
            if testStore.data.isEmpty {
                Text("Empty")
            } else {
                Form {
                    ForEach(testStore.data.indices, id: \.self) { index in
                        TestRow(test: $testStore.data[index], deleteHandler: { testStore.data.remove(at: index) })
                    }
                }
            }
        }
    }
}

struct TestRow: View {
    
    @Binding var test: Test
    let deleteHandler: (() -> ())
    
    var body: some View {
        HStack {
            Text(test.text)
                .font(.headline)
            Spacer()
            Button(action: deleteHandler, label: Image(systemName: "trash"))
        }
    }
}

Does this answer your question? [SwiftUI ForEach index out of range error when removing row](https://stackoverflow.com/questions/59060673/swiftui-foreach-index-out-of-range-error-when-removing-row) — Andrew, Jan 10 '21 at 14:10
@Andrew unfortunately no, I've searched all SO to no avail. You're welcome to try the code yourself. — Peter Warbo, Jan 10 '21 at 14:13
What are you using the `@Binding` for in the TestRow? In your example it seems superfluous — Andrew, Jan 10 '21 at 14:15
Remove @Binding from row view, if you don’t want to update row view — Raja Kishan, Jan 10 '21 at 14:16
Check this, it’s similar: https://stackoverflow.com/a/59007863/14733292 — Raja Kishan, Jan 10 '21 at 14:26
Remove binding and instead of this pass testStore object and index — Raja Kishan, Jan 10 '21 at 14:29
Does this answer your question? [Deleting list elements from SwiftUI's List](https://stackoverflow.com/questions/63079221/deleting-list-elements-from-swiftuis-list) — pawello2222, Jan 10 '21 at 16:17
@pawello2222 it helps a little bit with `Safe` but that makes me have to use `List` instead of `ForEach` which I need... — Peter Warbo, Jan 11 '21 at 16:44

score 1 · Accepted Answer · answered Jan 12 '21 at 00:02

You can use the extension proposed here:

struct Safe<T: RandomAccessCollection & MutableCollection, C: View>: View {
    typealias BoundElement = Binding<T.Element>
    private let binding: BoundElement
    private let content: (BoundElement) -> C

    init(_ binding: Binding<T>, index: T.Index, @ViewBuilder content: @escaping (BoundElement) -> C) {
        self.content = content
        self.binding = .init(get: { binding.wrappedValue[index] },
                             set: { binding.wrappedValue[index] = $0 })
    }

    var body: some View {
        content(binding)
    }
}

Then, if you also want to keep ForEach instead of List you can do:

struct TestList: View {
    @EnvironmentObject var testStore: Test.Store

    var body: some View {
        Group {
            if testStore.data.isEmpty {
                Text("Empty")
            } else {
                Form {
                    ForEach(testStore.data.indices, id: \.self) { index in
                        Safe($testStore.data, index: index) { binding in
                            TestRow(test: binding, deleteHandler: { testStore.data.remove(at: index) })
                        }
                    }
                }
            }
        }
    }
}

Crash when array is empty in iOS 14.3

1 Answers1