SwiftUI auto navigates to detail view after saving and dismissing the view - ios

Question

So I am writing a todo list app in SwiftUI in order to get the hang of it, but I am facing a problem.
In my first view (list of items) I have a toolbar with an "add" button which uses a NavigationLink to navigate to the detail view. In the detail view I also have a toolbar button acting as a save button which dismisses this view and also adds the item to a list of items kept in the view model used by both views.
The problem is that if I save the item when tapping the save button it will first navigate back to the first view and then auto navigate to the second view again. If I instead use the built in back button this issue doesn't happen, but obviously I would like to save the item and only when pressing save. This also only happens if I add the item to the item list in the view model before dismissing the view, if I only dismiss the view without saving the item when pressing done then this bug doesn't happen.
Is this not a standard way of saving and closing a view with SwiftUI, or is there some sort of other pattern that is better? In any case I need to resolve this issue.
First view:
struct TodoListView: View {
#EnvironmentObject var viewModel: TodoListViewModel
var body: some View {
NavigationView {
List {
ForEach(viewModel.listOfTodos) { todoItem in
ItemCellView(todoItem: todoItem)
}
}
.navigationTitle("Things to do")
.toolbar {
ToolbarItem(placement: .navigationBarTrailing) {
NavigationLink(
destination: AddEditTodoView(todoItem: TodoListInfo.TodoItem())
) {
Text("Add item") // The navigation bug happens when using this button
}
}
}
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
struct ItemCellView: View {
var todoItem: TodoListInfo.TodoItem
var body: some View {
HStack {
NavigationLink(destination: AddEditTodoView(todoItem: todoItem)) {
Text(todoItem.title) // The navigation bug doesn't happen when editing an existing item
}
}
.padding()
}
}
Second view:
struct AddEditTodoView: View {
#Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
#EnvironmentObject var viewModel: TodoListViewModel
#State var todoItem: TodoListInfo.TodoItem
var body: some View {
Form {
Section(header: Text("Title")) {
TextField("Title", text: $todoItem.title)
}
}
.navigationTitle(Text("Edit task"))
.toolbar {
ToolbarItem(placement: .navigationBarTrailing) {
Button("Done") {
viewModel.upsert(item: todoItem) // No bug if I comment out this line
presentationMode.wrappedValue.dismiss()
}
.disabled(todoItem.title == "")
}
}
}
}
View model:
class TodoListViewModel: ObservableObject {
#Published private var todoListInfo: TodoListInfo
private var autoSaveCancellable: AnyCancellable? // even without the autoSaveCancellable part, the bug happens
init(testData: Bool = false) {
todoListInfo = TodoListInfo(testData: testData)
autoSaveCancellable = $todoListInfo.sink {
TodoListInfo.persistTodoList($0)
}
}
var listOfTodos: [TodoListInfo.TodoItem] {
todoListInfo.todos
}
func upsert(item: TodoListInfo.TodoItem) {
if let itemIndex = todoListInfo.todos.firstIndex(where: { $0.id == item.id }) {
todoListInfo.todos[itemIndex] = item
} else {
todoListInfo.todos.append(item) // This gets called when adding an item
}
}
}

Answer 1

The solution for this is to make the navigation be based on a binding state.
NavigationLink(
destination: ExchangeItemSelectedView(exchange: observer),
tag: exchange.id,
selection: $exchangeSelection
) {
Text("Tap Me")
}
then rather than using #State to store exchangeSelection use #SceneStorage this will let you access the binding from anywhere within your app, in the code that creates the new item it should then dispatch async to update the selection value to the new item ID.