How to make view update when CoreData entity changes - swift

Question

Update
Based on #Tushar Sharma's suggestion, I removed #ObservedObject tag from the place variable in both PlaceDetail.swift and EditPlaceForm.swift. This made it so that the place property was an argument for the view rather than a state object. I then created separate state variables in EditPlaceForm.swift to hold the values for the text inputs. I added an onAppear to the view that sets the state values using the provided place object. This works great, and resolves the issue of the back button disappearing. It introduced a new problem though: PlaceDetail doesn't update until after it's been closed and reopened. I then did some testing to see if updating the place variable within PlaceDetail itself caused an update. To do this I just added a button that changed the name of the place and saved it to the view context when pressed. The view still did not update until it was reloaded. Therefore, my question has switched to how to make the view update when place is updated, without using #ObservedObject in EditPlaceForm.swift, which caused the back button to disappear.
Updated Pieces of Code
PlaceDetail.swift
Original:
#ObservedObject var place: Place
Updated:
var place: Place
EditPlaceForm.swift
Updated:
//
// EditPlaceForm.swift
//
import SwiftUI
import CoreLocation
struct EditPlaceForm: View {
#Environment(\.presentationMode) private var presentationMode
#Environment(\.managedObjectContext) private var viewContext
var place: Place
#State private var name = ""
#State private var street = ""
#State private var city = ""
#State private var state = ""
#State private var zip = ""
#State private var country = ""
#State private var showAlert = false
#State private var alertText = ""
var body: some View {
NavigationView {
Form {
Section (header: Text("Name")) {
TextField("Name", text: $name)
}
Section (header: Text("Address")) {
VStack {
TextField("Street", text: $street)
TextField("City", text: $city)
HStack {
TextField("State", text: $state)
Divider()
TextField("ZIP", text: $zip)
}
TextField("Country", text: $country)
}
}
Section(header: Text("Save")) {
Button (action: {
save()
}, label: {
Text("Save")
})
}
}
.navigationTitle("Edit Place")
.alert(isPresented: $showAlert, content: {
Alert(title: Text("Error"), message: Text(alertText))
})
}
.onAppear {
loadPlaceData()
}
}
func loadPlaceData() {
name = place.name
street = place.street
city = place.city
state = place.state
zip = place.zip
country = place.country
}
func save() {
let geocoder = CLGeocoder()
geocoder.geocodeAddressString("\(street), \(city) \(state), \(zip), \(country)", completionHandler: {
placemarks, error in
if error != nil {
print("Error forward geocoding")
print(error!.localizedDescription)
alertText = "Encountered geocoding error."
showAlert = true
return
}
if placemarks == nil {
print("No placemarks found")
alertText = "Location could not be found."
showAlert = true
return
}
let placemark = placemarks![0]
let testVars = [
placemark.thoroughfare,
placemark.locality,
placemark.administrativeArea,
placemark.country,
placemark.postalCode
]
for testVar in testVars {
if testVar == nil {
print("Not enough information to complete place")
alertText = "Not enough information."
showAlert = true
return
}
}
if placemark.location == nil {
print("Not enough information to complete place")
alertText = "Not enough information."
showAlert = true
return
}
viewContext.performAndWait {
place.street = placemark.subThoroughfare! + " " + placemark.thoroughfare!
place.city = placemark.locality!
place.state = placemark.administrativeArea!
place.country = placemark.country!
place.zip = placemark.postalCode!
place.latitude = placemark.location!.coordinate.latitude
place.longitude = placemark.location!.coordinate.latitude
do {
try viewContext.save()
presentationMode.wrappedValue.dismiss()
} catch {
print("ERROR: FAILED TO SAVE PLACE DETAILS")
alertText = "Failed to save."
showAlert = true
}
}
})
}
}
struct EditPlaceForm_Previews: PreviewProvider {
private static var viewContext = PersistenceController.preview.container.viewContext
static var previews: some View {
EditPlaceForm(place: Place.getDefault(context: viewContext))
}
}
Original Post
Setup
My app has a main page which is a navigation view. On that page, there are navigation links. One of those links leads to the "Places" page which contains a list. The list items on that page are navigation links to detail pages for CoreData entities called Place. In the detail pages I have an edit button that opens an editing form as a sheet.
Intended Behavior
You open the details view from the "Places" view, using the navigation link. You then click the edit button and change some of the information. When you click save, the editing form closes and the changes are reflected in the details view. You can then click the back button to go back to the "Places" view.
Current Behavior
You open the details view from the "Places" view, using the navigation link. You then click the edit button and change some of the information. When you save, the editing form closes and the changes are reflected in the details view, but the back button has disappeared and you are stuck in the details view.
Video: https://drive.google.com/file/d/1lzj-hOCb7hgMutQQwPl0ShR7l-c9sDib/view?usp=sharing
Code
"Places" view:
//
// PlacesList.swift
//
import SwiftUI
struct PlacesList: View {
#Environment(\.managedObjectContext) private var viewContext
#FetchRequest(entity: Place.entity(), sortDescriptors: [
NSSortDescriptor(key: "name", ascending: true)
])
private var places: FetchedResults<Place>
#State private var showAddPlaceForm = false
var body: some View {
List {
ForEach (places) { place in
NavigationLink (destination: PlaceDetail(place: place)) {
PlaceRow(place: place)
}
}
.onDelete(perform: deleteRow)
}
.listStyle(PlainListStyle())
.navigationTitle(Text("Places"))
.navigationBarItems(trailing:
HStack {
Button(action: {
showAddPlaceForm = true
}, label: {
Image(systemName: "plus.circle")
.imageScale(.large)
})
.sheet(isPresented: $showAddPlaceForm) {
NewPlaceForm()
}
}
)
}
func deleteRow(at offsets: IndexSet) {
for offset in offsets {
viewContext.performAndWait {
viewContext.delete(places[offset])
try? viewContext.save()
}
}
}
}
struct PlacesList_Previews: PreviewProvider {
private static var viewContext = PersistenceController.preview.container.viewContext
static var previews: some View {
NavigationView {
PlacesList()
.environment(\.managedObjectContext, PersistenceController.preview.container.viewContext)
}
}
}
PlaceRow.swift
//
// PlaceRow.swift
//
import SwiftUI
struct PlaceRow: View {
#Environment(\.managedObjectContext) private var viewContext
#ObservedObject var place: Place
var body: some View {
VStack (alignment: .leading) {
Text(place.name)
.font(.headline)
Group {
Text(place.street)
Text(place.city) + Text(", ") + Text(place.state)
}
.font(.subheadline)
.foregroundColor(.secondary)
}
}
}
struct PlaceRow_Previews: PreviewProvider {
private static var viewContext = PersistenceController.preview.container.viewContext
static var previews: some View {
List {
PlaceRow(place: Place.getDefault(context: viewContext))
}
}
}
PlaceDetail.swift
//
// PlaceDetail.swift
//
import SwiftUI
import CoreLocation
struct PlaceDetail: View {
#Environment(\.managedObjectContext) private var viewContext
#ObservedObject var place: Place
#State private var showEditForm = false
var body: some View {
List {
VStack (alignment: .leading) {
Text("Address")
.font(.headline)
Group {
Text(place.street)
Text(place.cityStateZIPString)
Text(place.country)
}
.font(.subheadline)
.foregroundColor(.secondary)
}
VStack {
MapView(place: place)
.frame(height: 300)
}
if place.encodedAddress != nil {
Link(destination:
URL(string: "http://maps.apple.com/?daddr=\(place.encodedAddress!)")!,
label: {
HStack {
Text("Get Directions with Apple Maps")
Spacer()
Image(systemName: "chevron.forward.circle")
.imageScale(.large)
}
.foregroundColor(.blue)
})
Link(destination:
URL(string: "https://www.google.com/maps/search/?api=1&destination=\(place.encodedAddress!)")!,
label: {
HStack {
Text("Get Directions with Google Maps")
Spacer()
Image(systemName: "chevron.forward.circle")
.imageScale(.large)
}
.foregroundColor(.blue)
})
}
}
.toolbar {
Button(action: {
showEditForm = true
}, label: {
Image(systemName: "pencil.circle")
})
}
.navigationTitle(place.name)
.sheet(isPresented: $showEditForm, content: {
EditPlaceForm(place: place)
})
}
}
struct PlaceDetail_Previews: PreviewProvider {
static var viewContext = PersistenceController.preview.container.viewContext
static var previews: some View {
NavigationView {
PlaceDetail(place: Place.getDefault(context: viewContext))
.environment(\.managedObjectContext, viewContext)
}
}
}
EditPlaceForm.swift
//
// EditPlaceForm.swift
//
import SwiftUI
import CoreLocation
struct EditPlaceForm: View {
#Environment(\.presentationMode) private var presentationMode
#Environment(\.managedObjectContext) private var viewContext
#ObservedObject var place: Place
#State private var showAlert = false
#State private var alertText = ""
var body: some View {
NavigationView {
Form {
Section (header: Text("Name")) {
TextField("Name", text: $place.name)
}
Section (header: Text("Address")) {
VStack {
TextField("Street", text: $place.street)
TextField("City", text: $place.city)
HStack {
TextField("State", text: $place.state)
TextField("ZIP", text: $place.zip)
}
TextField("Country", text: $place.country)
}
}
Section(header: Text("Save")) {
Button (action: {
save()
}, label: {
Text("Save")
})
}
}
.navigationTitle("Edit Place")
.alert(isPresented: $showAlert, content: {
Alert(title: Text("Error"), message: Text(alertText))
})
}
}
func save() {
let geocoder = CLGeocoder()
geocoder.geocodeAddressString(place.address, completionHandler: {
placemarks, error in
if error != nil {
print("Error forward geocoding")
print(error!.localizedDescription)
alertText = "Encountered geocoding error."
showAlert = true
return
}
if placemarks == nil {
print("No placemarks found")
alertText = "Location could not be found."
showAlert = true
return
}
let placemark = placemarks![0]
let testVars = [
placemark.thoroughfare,
placemark.locality,
placemark.administrativeArea,
placemark.country,
placemark.postalCode
]
for testVar in testVars {
if testVar == nil {
print("Not enough information to complete place")
alertText = "Not enough information."
showAlert = true
return
}
}
if placemark.location == nil {
print("Not enough information to complete place")
alertText = "Not enough information."
showAlert = true
return
}
viewContext.performAndWait {
place.street = placemark.subThoroughfare! + " " + placemark.thoroughfare!
place.city = placemark.locality!
place.state = placemark.administrativeArea!
place.country = placemark.country!
place.zip = placemark.postalCode!
place.latitude = placemark.location!.coordinate.latitude
place.longitude = placemark.location!.coordinate.latitude
do {
try viewContext.save()
presentationMode.wrappedValue.dismiss()
} catch {
print("ERROR: FAILED TO SAVE PLACE DETAILS")
}
}
})
}
}
struct EditPlaceForm_Previews: PreviewProvider {
private static var viewContext = PersistenceController.preview.container.viewContext
static var previews: some View {
EditPlaceForm(place: Place.getDefault(context: viewContext))
}
}