I'm trying to migrate my app from using NavigationView to NavigationStack and have run into an issue. It seems that when a View has a state variable with an optional type that's initialised as nil, then asynchronously changes to something other than nil, the view doesn't update.
If I use NavigationView it works fine, and if I initialise the state variable with something other than nil it also works fine.
I can't figure out why – any advice is appreciated. This is on iOS 6 beta 3.
struct ContentView: View {
// Initialise this as something other than nil and it'll work
// e.g. @State private var foo: String? = ""
@State private var foo: String? = nil
var body: some View {
// Change this to NavigationView and it'll work.
NavigationStack {
if let foo { Text(foo) }
// ProgressView never goes away
else { ProgressView() }
}
.task {
// Simulate loading some data asynchronously.
DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
foo = "loaded"
}
}
}
}
From the iOS & iPadOS 16 Beta 3 Release Notes:
Conditional views in columns of
NavigationSplitViewfail to update on some state changes. (91311311)Workaround: Wrap the contents of the column in a
ZStack.
It mentions NavigationSplitView, but it must apply to NavigationStack as wrapping the if statement in your example in a ZStack updates the view.
