如何防止在 SwiftUI 中重新创建条件视图？

Question

I have a parent view that conditionally displays a subview:

struct HomeView: View {    
    @State var selectedView = true

    var body: some View {
        VStack {
            Picker("Selected", selection: $selectedView) {
                Text("A").tag(true)
                Text("B").tag(false)
            }.pickerStyle(SegmentedPickerStyle())
            
            if selectedView {
                SubView()
            } else {
                Text("Other")
            }
        }
    }
}

My subview contains an AsyncImage that loads from a URL:

struct SubView: View {
    private let url = URL(string: "some url here")
    var body: some View {
        AsyncImage(url: url)
    }
}

My issue is that SubView is recreated every time I switch the picker to B and then back to A. This recreates the AsyncImage and causes a reload from the URL, which is not necessary.

Is there a way to prevent SubView from being recreated here? I notice that TabView does not seem to recreate its containing views when switching between them. Is it possible to get this functionality using the structure I have?

I have tried making SubView equatable and using the .equatable() modifier on its instance as such:

if selectedView {
    SubView().equatable()
} else {
    Text("Other")
}

However, the image is still reloaded.

Answer 1

Either get rid of the if that creates a _ConditionView and use a modifier instead, or enable the URLSession 's URLCache so the image is cached in memory on or disk and isn't actually downloaded again.