LazyVStack Error using ForEach

Question

My app crashes on iPhone/iPad Simulator when I'm using 2 ForEach in a LazyVStack. In the Canvas is works perfectly fine.

Error message is: 'Fatal error: each layout item may only occur once'

Minimum example:

Code Block swiftstruct ContentView: View {
    var body: some View {
        ScrollView {
            LazyVStack{
                ForEach(0...2, id: \.self) { _ in
                    Section {
                        ForEach(0..<2, id: \.self) { idx in
                            Text("Section Cell \(idx)")
                        }
                    }
                }
            }
        }
    }
}

If you change the LazyVStack with Vstack it work and if you delete one of the ForEach it work also on the simulator.

4.6k

Posted by

HeGer

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Answer 1

The problem is the fact that in your code you end up with repeated identifiers and I believe that LazyVStack requires the ids to be unique. I managed to make it work using a UUID as an identifier:

Code Block swiftstruct ContentView: View {
    var body: some View {
        ScrollView {
            LazyVStack{
                ForEach(0...2, id: \.self) { section in
                    Section {
                        ForEach(0..<2) { item in
                            Text("Section: \(section), Item: \(item)")
                                .id(UUID())
                        }
                    }
                }
            }
        }
    }
}

Posted by

mtsrodrigues

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Answer 2

The problem is the fact that in your code you end up with repeated identifiers and I believe that LazyVStack requires the ids to be unique. I managed to make it work using a UUID as an identifier:

Code Block swiftstruct ContentView: View {
    var body: some View {
        ScrollView {
            LazyVStack{
                ForEach(0...2, id: \.self) { section in
                    Section {
                        ForEach(0..<2) { item in
                            Text("Section: \(section), Item: \(item)")
                                .id(UUID())
                        }
                    }
                }
            }
        }
    }
}

Posted by

mtsrodrigues

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LazyVStack Error using ForEach

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