ProgressView inside SwiftUI List disappearing after list is updated

Question

The circular (default) SwiftUI ProgressView disappears within a List whenever the list gets expanded with new content because of a .onAppear modifier on the ProgressView.

The ProgressView becomes invisible, although its allocated cell (and its label, if assigned) within the list remain visible.

I want to keep the ProgressView at the bottom of the list so that the list gets automatically updated with new content being downloaded from the server when the user reaches the end of the list.

Possible duplicate of this article but the accepted answer does not tackle the reason why the view disappears.

Reprex:

struct ContentView: View {
    
    @State var items: [String] = ["Item 1", "Item 2", "Item 3", "Item 4", "Item 5", "Item 6"]
        
    var body: some View {
        List {
            ForEach(items, id: \.self) { item in
                Text(item)
                    .frame(height: 100)
            }
            
            ProgressView {
                Text("Loading")
            }
            .frame(maxWidth: .greatestFiniteMagnitude, alignment: .center)
            .onAppear(perform: endOfListReached)
        }
    }
    
    func endOfListReached() {
        DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
            items.append("Item \(items.count + 1)")
        }
    }
}

do you have to have a `List` or would a `ScrollView` be acceptable. — workingdog support Ukraine, Feb 11 '23 at 02:41

score 1 · Accepted Answer · answered Feb 20 '23 at 10:49

1

I would rather keep the List for its convenient layout, but it appears that the List is causing the issue here and that changing it to a ScrollView and LazyVStack and styling it with Dividers works as expected.

answered Feb 20 '23 at 10:49

Thofreym

59
6

Just clarify that the ProgressView has to be inside the LazyVStack. Otherwise the .onAppear event only happens once. – zephyr Mar 02 '23 at 03:44
@zephyr correct! – Thofreym Mar 10 '23 at 15:07
Thanks! I've also learned about ScrollView + LazyVStack. It's the same than using a List view? – Fede Cugliandolo Jun 30 '23 at 20:14

ProgressView inside SwiftUI List disappearing after list is updated

1 Answers1