Programmatic Navigation Weird Behaviour with CoreData - core-data

Question

I have a list of items stored in CoreData and an add button on the top right which adds an item to the list and navigates to the ItemView programmatically.
When there is no item in the list and I press the add button the created item slides in as expected but the NavigationLink doesn't navigate to its ItemView automatically. Furthermore, the NavigationLink doesn't even work when tapping on it.
Only when pressing the add button again - which slides in the second item - do the NavigationLinks start to work as expected.
Steps to reproduce:
Create a new Single View App and click CoreData and Hosted in CloudKit. There should be an Item Entity stored in CoreData already.
Replace the ContentView.swift with this:
import SwiftUI
import CoreData
struct ContentView: View {
#Environment(\.managedObjectContext) private var viewContext
#State private var selection: Date?
#FetchRequest(
sortDescriptors: [NSSortDescriptor(keyPath: \Item.timestamp, ascending: true)],
animation: .default)
private var items: FetchedResults<Item>
var body: some View {
NavigationView {
List {
ForEach(items) { item in
NavigationLink(
"Item at \(item.timestamp!, formatter: itemFormatter)",
destination: ItemView(item: item),
tag: item.timestamp!,
selection: $selection
)
}
.onDelete(perform: deleteItems)
}
.listStyle(InsetGroupedListStyle())
.navigationTitle("Items")
.toolbar {
Button(action: addItem) {
Label("Add Item", systemImage: "plus")
}
}
}
}
private func addItem() {
withAnimation {
let newItem = Item(context: viewContext)
newItem.timestamp = Date()
do {
try viewContext.save()
} catch {
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
let nsError = error as NSError
fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
}
selection = newItem.timestamp
}
}
private func deleteItems(offsets: IndexSet) {
withAnimation {
offsets.map { items[$0] }.forEach(viewContext.delete)
do {
try viewContext.save()
} catch {
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
let nsError = error as NSError
fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
}
}
}
}
struct ItemView: View {
let item: Item
var body: some View {
Text("Item at \(item.timestamp!, formatter: itemFormatter)")
}
}
private let itemFormatter: DateFormatter = {
let formatter = DateFormatter()
formatter.dateStyle = .short
formatter.timeStyle = .medium
return formatter
}()
Click on the add button on the top right. Then try to click on the NavigationLink. It won't navigate. Only when pressing the add button again will it work as expected.

Answer 1

I update the selection asynchronously after 0.5 seconds and the bug disappears. Not sure if this is a reliable solution but from the user's perspective it is intuitive to first see the item slide in and navigating after.
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
selection = newItem.timestamp
}