I have a background thread that is updating a swift data model Item
using a ModelActor
. The background thread runs processing an Item
and updates the Item
's status
field. I notice that if I have a view like
struct ItemListView: View {
@Query private var items: [Items]
var body: some View {
VStack {
ForEach(items) { item in
ItemDetailView(item)
}
}
}
}
struct ItemDetailView: View {
var item: Item
var body: some View {
// expected: item.status automatically updates when the background thread updates the `Item`'s `status`.
Text(item.status)
// actual: This text never changes
}
}
Then background updates to the Item
's status
in SwiftData does not reflect in the ItemDetailView
. However, if I inline ItemDetailView
in ItemListView
like this:
struct ItemListView: View {
@Query private var items: [Items]
var body: some View {
VStack {
ForEach(items) { item in
// Put the contents of ItemDetailView directly in ItemListView
Text(item.status)
// result: item.status correctly updates when the background thread updates the item.
}
}
}
}
Then the item's status
text updates in the UI as expected. I suspect ItemDetailView
does not properly update the UI because it just takes an Item
as an input. ItemDetailView
would need additional understanding of SwiftData, such as a ModelContext.
Is there a way I can use ItemDetailView
to show the Item
's status and have the UI show the status as updated in the background thread?
In case details about my background thread helps solve the problem, my thread is invoked from another view's controller like
@Observable
class ItemCreateController {
func queueProcessingTask() {
Task {
let itemActor = ItemActor(modelContainer: modelContainer)
await itemActor.setItem(item)
await itemActor.process()
}
}
}
@ModelActor
actor ItemActor {
var item: Item?
func setItem(_ item: Item) {
self.item = modelContext.model(for: item.id) as? Item
}
func process() async {
// task that runs processing on the Item and updates the Item's status as it goes.
}