Content in scrollview as a list item disappears when scrolling (swiftui), why?

Question

Solution by @Asperi, ScrollView().id(UUID().uuidString).

There is a scrollview in the list item, when I scroll the list, the content in scrollview disappears.

I think the issue is about scrollview & list reusable item conflict.

If I remove scrollview(just hstack{}), nothing disappears. So I think it's scrollview's issue. Any ideal?

struct ContentView: View {
    var body: some View {
        List {
            ForEach(0...100, id: \.self) { _ in
                ItemView().padding()
            }
        }
    }
}

struct ItemView: View {
    var body: some View {
        VStack(alignment: .leading) {
            Text("Tag list:")
            ScrollView(.horizontal, showsIndicators: false) {
                HStack {
                    ForEach(0...8, id: \.self) { _ in
                        TagView1()
                    }
                }
            }.id(UUID().uuidString) /// <- fix
        }
    }
}

struct TagView1: View {
    var body: some View {
        Text("Tag\(String(UUID().uuidString.prefix(5)))")
            .foregroundColor(.secondary)
            .padding(.horizontal, 2)
            .background(RoundedRectangle(cornerRadius: 4).stroke(Color.secondary.opacity(0.5)))
            .padding(1)
    }
}

Martijn Pieters · Accepted Answer · 2022-08-23 07:16:11Z

12

If I correctly understood what disappears (I assume you meant list rows on vertical scrolling), then yes it is due to List reuse/cache optimisation issue.

The following approach should work (tested with Xcode 11.2 / iOS 13.2)

struct ItemView: View {
    var body: some View {
        VStack {
            Text("Tag list:")
            ScrollView(.horizontal, showsIndicators: false) {
                HStack {
                    ForEach(0...8, id: \.self) { _ in
                        TagView().padding()
                    }
                }
            }.id(UUID().uuidString) // << here is a fix !
        }
    }
}

edited Aug 23, 2022 at 7:16

Martijn Pieters

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answered Jan 19, 2020 at 15:07

Asperi

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3 Comments

foolbear Over a year ago

I modify the post.

foolbear Over a year ago

the container must be list, can not be VStack.

foolbear Over a year ago

ScrollView().id(UUID().uuidString) is the key resolution, thanks @Asperi.

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