Saving Item in CoreData Initiates Navigation - core-data

Question

In my ContentView I have a FetchRequest<Project>. I navigate to ProjectView using a NavigationLink. From ProjectView I navigate to AddItemView using another NavigationLink. In AddItemView when I add an Item to the Project and call container.viewContext.save() the AddItemView automatically dismisses back to the ContentView.
My guess is that saving to CoreData updates the FetchRequest<Project> list which in turn updates the views, but I am not sure.
How can I save a new Item to the Project in CoreData and only navigate back to ProjectView and not ContentView?
To reproduce:
Create new Single View App and check Core Data and Host in CloudKit
In the .xcdatamodel delete the default Entity and replace it with an Entity called Project which has attributes date: Date and title: String and an Entity called Item which has an attribute name: String. Give the Project a relationship called items (to type Item) and choose “to many” on the right. Give the Item a relationship called project that is the inverse of items.
Replace the code in Persistence.swift with this:
// Persistence.swift
import CoreData
struct PersistenceController {
static let shared = PersistenceController()
let container: NSPersistentCloudKitContainer
init(inMemory: Bool = false) {
container = NSPersistentCloudKitContainer(name: "CoreDataBug")
if inMemory {
container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
}
container.loadPersistentStores(completionHandler: { (storeDescription, error) in
if let error = error as NSError? {
// 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.
/*
Typical reasons for an error here include:
* The parent directory does not exist, cannot be created, or disallows writing.
* The persistent store is not accessible, due to permissions or data protection when the device is locked.
* The device is out of space.
* The store could not be migrated to the current model version.
Check the error message to determine what the actual problem was.
*/
fatalError("Unresolved error \(error), \(error.userInfo)")
}
})
}
}
Copy ContentView
// ContentView.swift
import SwiftUI
struct ContentView: View {
#Environment(\.managedObjectContext) var moc
let projects: FetchRequest<Project>
init() {
projects = FetchRequest<Project>(entity: Project.entity(), sortDescriptors: [
NSSortDescriptor(keyPath: \Project.date, ascending: false)
])
}
var body: some View {
NavigationView {
List {
ForEach(projects.wrappedValue) { project in
NavigationLink(destination: ProjectView(project: project)) {
Text(project.title ?? "Title")
}
}
}
.navigationTitle("Projects")
.toolbar {
ToolbarItem(placement: ToolbarItemPlacement.navigationBarTrailing) {
Button {
withAnimation {
let project = Project(context: moc)
let now = Date()
project.date = now
project.title = now.description
try? moc.save()
}
} label: {
Label("Add Project", systemImage: "plus")
}
}
}
}
}
}
Create ProjectView.swift and copy this:
// ProjectView.swift
import SwiftUI
struct ProjectView: View {
#ObservedObject var project: Project
var items: [Item] {
project.items?.allObjects as? [Item] ?? []
}
var body: some View {
List {
ForEach(items) { item in
Text(item.name ?? "")
}
}
.toolbar {
ToolbarItem(placement: ToolbarItemPlacement.navigationBarTrailing) {
NavigationLink(destination: AddItemView(project: project)) {
Label("Add Item", systemImage: "plus")
}
}
}
}
}
Create AddItemView.swift and copy this:
import SwiftUI
// AddItemView.swift
import SwiftUI
struct AddItemView: View {
#Environment(\.presentationMode) var presentationMode
#Environment(\.managedObjectContext) var moc
let project: Project
#State private var selectedName: String = ""
var body: some View {
TextField("Type name here", text: $selectedName)
.navigationTitle("Add Item")
.navigationBarItems(trailing: Button("Add") {
let ingestion = Item(context: moc)
ingestion.project = project
ingestion.name = selectedName
try? moc.save()
presentationMode.wrappedValue.dismiss()
})
}
}
Run the app. Click the plus on the top right. Click the project that just slid in. In the ProjectView click the plus on the top right again. Type a name in the TextField and click add on the top right. When the AddItemView is dismissed it probably went back to ContentView. If not add another item to the project.