Hello. I’ve encountered a strange issue with TimelineView and wanted to report it.
The following code runs without any problems:
// Example 1.
struct ContentView: View {
var body: some View {
TimelineView(.everyMinute) { _ in
List {
TimelineView(.everyMinute) { _ in
Text("Hello")
}
}
}
}
}
However, the code below causes the CPU usage to spike to 100%, and the screen displays a blank view:
// Example 2.
struct ContentView: View {
var body: some View {
TimelineView(.everyMinute) { _ in
List {
TimelineView(.everyMinute) { _ in
text
}
}
}
}
var text: some View {
Text("Hello")
}
}
The same issue occurs with the following code:
// Example 3.
struct MyTextView: View {
var body: some View {
Text("Hello")
}
}
struct ContentView: View {
var body: some View {
TimelineView(.everyMinute) { _ in
List {
TimelineView(.everyMinute) { _ in
MyTextView()
}
}
}
}
}
Replacing List with LazyVStack and ForEach resolves the hang issue, but I need to use List because I rely on the swipeActions().
Does anyone have insights or suggestions on how to address this issue?
Ukjeong Lee
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To apply custom transition animations, I implemented a UIViewControllerRepresentable wrapping UINavigationController instead of using NavigationStack.
The navigation stack pops correctly with DismissAction.
However, when I call DismissAction after presenting my CustomNavigationStack with fullScreenCover(isPresented:onDismiss:content:), it doesn't work.
I suspect that the DismissAction implementation does not handle this case. Is there a workaround for this?
Below is a simple reproduction code:
struct ChildView: View {
@Environment(\.dismiss) private var dismiss
var body: some View {
Button {
dismiss()
} label: {
Text(verbatim: "Dismiss!!")
.background(Color.yellow)
}
}
}
struct CustomSimpleVC: UIViewControllerRepresentable {
func makeUIViewController(context: Context) -> UIHostingController<ChildView> {
let vc = UIHostingController(rootView: ChildView())
vc.view.backgroundColor = .green
return vc
}
func updateUIViewController(_ uiViewController: UIHostingController<ChildView>, context: Context) {}
}
struct CustomContainerVC: UIViewControllerRepresentable {
func makeUIViewController(context: Context) -> UIViewController {
let childVC = UIHostingController(rootView: ChildView())
childVC.view.backgroundColor = .blue
let vc = UIViewController()
vc.addChild(childVC)
vc.view.addSubview(childVC.view)
childVC.view.frame = vc.view.bounds
childVC.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
childVC.didMove(toParent: vc)
return vc
}
func updateUIViewController(_ uiViewController: UIViewController, context: Context) {}
}
struct CustomNavigationVC: UIViewControllerRepresentable {
func makeUIViewController(context: Context) -> UINavigationController {
let childVC = UIHostingController(rootView: ChildView())
childVC.view.backgroundColor = .red
let childVC2 = UIHostingController(rootView: ChildView())
childVC2.view.backgroundColor = .gray
let navVC = UINavigationController()
navVC.viewControllers = [childVC, childVC2]
return navVC
}
func updateUIViewController(_ uiViewController: UINavigationController, context: Context) {}
}
struct ContentView: View {
@State private var isNextPresented: Bool = false
var body: some View {
VStack {
Button {
isNextPresented = true
} label: {
Text(verbatim: "present")
}
}
.fullScreenCover(isPresented: $isNextPresented, content: {
VStack {
CustomSimpleVC() // Works
CustomContainerVC() // Works
CustomNavigationVC() // Does not work
}
})
}
}
#Preview {
ContentView()
}