SwiftUI conditional doesn't work at top level in view - swift

Question

I have a view model that looks like this:
class SegmentViewModel: ObservableObject {
#Published private(set) var itemIds = [Int]()
private var cancellables: Set<AnyCancellable> = []
init() {
fetchIds()
}
private func fetchIds() {
let request = URLRequest(path: "/ids")
network
.send(request)
.receive(on: DispatchQueue.main)
.sink { completion in
switch completion {
case .failure(let error): print(error.localizedDescription)
case .finished: break
}
} receiveValue: { response in
self.itemIds = response
}
.store(in: &cancellables)
}
}
That all works fine and then my View is as follows:
struct SegmentView: View {
#ObservedObject var viewModel: SegmentViewModel
var body: some View {
if viewModel.itemIds.isEmpty {
ProgressView()
} else {
ScrollView {
LazyVStack {
ForEach(viewModel.itemIds, id: \.self) { id in
ItemView(viewModel: ItemViewModel(itemId: id))
.cornerRadius(15)
.padding()
.shadow(radius: 3)
}
}
}
}
}
}
But this doesn't work. The ProgressView is never hidden and replaced with the ScrollView. However, if I change my view to:
struct SegmentView: View {
#ObservedObject var viewModel: SegmentViewModel
var body: some View {
ScrollView {
if viewModel.itemIds.isEmpty {
ProgressView()
} else {
LazyVStack {
ForEach(viewModel.itemIds, id: \.self) { id in
ItemView(viewModel: ItemViewModel(itemId: id))
.cornerRadius(15)
.padding()
.shadow(radius: 3)
}
}
}
}
}
}
Then it works as expected and hides the ProgressView once the itemIds aren't empty.
Why is this?

Answer 1

It looks like ViewBuidler consumed the condition and so it is not observed. I would wrap top at Group
struct SegmentView: View {
#ObservedObject var viewModel: SegmentViewModel
var body: some View {
Group { // << here !!
if viewModel.itemIds.isEmpty {
ProgressView()
} else {
ScrollView {
LazyVStack {
ForEach(viewModel.itemIds, id: \.self) { id in
ItemView(viewModel: ItemViewModel(itemId: id))
.cornerRadius(15)
.padding()
.shadow(radius: 3)
}
}
}
}
}
}
}