When remove intermediate screen from path I expect the same behaviour like removing view controller from UINavigationController.viewControllers in UIKit.
But now it evoke pop animation and recreate associated StateObject.
It looks like instead of remove specific view controller in hierarchy, it removes the last one and change content on previous.
Code example to reproduce (Open Screen1, then Screen2 and touch Pop previous button):
enum Screen: String {
case screen1
case screen2
}
struct ContentView: View {
@State var path: [Screen] = []
var body: some View {
NavigationStack(path: $path) {
VStack {
Text("Root")
Button("open Screen 1") {
path.append(.screen1)
}
}
.navigationDestination(for: Screen.self) {
switch $0 {
case .screen1: ScreenView1(path: $path)
case .screen2: ScreenView2(path: $path)
}
}
}
}
}
struct ScreenView1: View {
@Binding var path: [Screen]
var body: some View {
VStack {
Text("Screen 1")
Button("Pop") { path.removeLast() }
Button("open Screen 2") { path.append(.screen2) }
}
}
}
struct ScreenView2: View {
@Binding var path: [Screen]
@StateObject var viewModel: Screen2ViewModel = .init()
var body: some View {
VStack {
Text("Screen 2")
Button("Pop") { path.removeLast() }
Button("Pop previous") {
// !!! Here the problem
path.remove(at: path.count - 2)
}
.disabled(path.count < 2)
}
}
}
class Screen2ViewModel: ObservableObject {
init() {
print("Screen2ViewModel.init")
}
}
Screencast:
It is possible to avoid pop animation by modifying path in transaction without animation:
var transaction = Transaction()
transaction.disablesAnimations = true
withTransaction(transaction) {
path.remove(at: path.count - 2)
}
But my question is: it is possible to avoid screen associated StateObject recreating?
paella
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We have a problem with undesirable rebuild with Debug configuration for watchOS target dependencies.
There is a iOS project with watch extension target. Both have some SPM package dependency.
Build Active Architecture Only for Debug is Yes for both app/extension targets.
When build app, watch target is building not only for active arch(arm64) but also i386/x86_64.
It can be fixed by adding Excluded Architectures = i386 x86_64 for watch target.
But it don't help to avoid rebuild SPM package dependency for this architectures.