How do I navigate to another SwiftUI View when an Environment Object update is causing the same view to reload - ios

Question

What I'm trying to achieve: I'm a new SwiftUI developer. I'm trying to build a simple Address Book app. I have three views:
ContentView - The main view which contains all contacts in a List View with an Add Contact ('+') and Edit button at the top of the Navigation View
AddContact View - which has a "Name" and "Email" text field and a "Submit" button
DisplayContactDetails View - not relevant to this question.
I've created an Environment Object "myContacts" which is an array of "Contact" objects and passed it in the ContentView to keep track of all contacts in the Address Book
When the user navigates to AddContact View, adds a name and email and submits, I'd like the Environment Object "myContacts" to be updated and for the user to be navigated back to ContentView so they can see the Address Book with the new contact included.
Problem:
When the user presses "Submit" on AddContact View, it correctly invokes a navigation link I've created to send the user back to ContentView. But because the Environment Object "myContacts" has also been updated by submit, it immediately navigates back from ContentView to AddContact View again. So it appears to be executing the Navigation Link first but then reloading AddContact View due to the refresh of myContacts.
Code - Content view:
struct ContentView: View {
#EnvironmentObject var myContacts: Contacts
#State var isAddButtonPressed: Bool = false
var body: some View {
NavigationView{
List {
ForEach(myContacts.contacts) { item in
NavigationLink(
//Display items and send user to DisplayContactDetails
})
}
}
.navigationBarTitle("Address Book")
.toolbar {
ToolbarItem(placement: .navigationBarLeading){
Button(action: {
isAddButtonPressed.toggle()
}, label: {
NavigationLink(
destination: AddContactView(),
isActive: $isAddButtonPressed,
label: {
Image(systemName: "plus")
})
})
}
ToolbarItem(placement: .navigationBarTrailing){
EditButton()
}
}
}
}
}
Code - AddContactView
struct AddContactView: View {
#State var name: String = ""
#State var email: String = ""
#State var isButtonPressed: Bool = false
#EnvironmentObject var myContacts: Contacts
var body: some View {
VStack{
HStack{
Text("Name:")
TextField("Enter name", text: $name)
}
.padding(.bottom, 50)
HStack{
Text("Email:")
TextField("Enter email", text: $email)
}
.padding(.bottom, 50)
Button("Submit") {
let contactToAdd = Contact(name: name, email: email)
//Add is a simple function - all it does is append an item to the myContacts array using the .append method
myContacts.add(contact: contactToAdd)
isButtonPressed = true
}
.frame(width: 80, height: 30, alignment:.center)
.background(Color.blue)
.foregroundColor(.white)
.clipShape(Capsule())
NavigationLink(destination: ContentView().navigationBarHidden(true),
isActive: $isButtonPressed,
label: {
EmptyView()
}).hidden()
}.padding()
}
}
What I've tried
If I comment out the the .add method and don't update the environment object, then the navigation back to ContentView works as expected. So I know that specifically is the cause of the problem.
I've tried adding a .onTapGesture modifier to the Button and invoking .add there.
I've tried adding a .onDisappear modifier to the entire view and invoking .add there.
--
Any help or clarity on resolving this would be much appreciated
Edit: Screen Recording - trying solution based on first comment:
What happens when I try the solution
Odd behaviour: The first attempt at adding a contact auto-routes back to AddContactView, producing the same error. But if I try it a second time then it routes correctly to ContactView.

Answer 1

Edit update. This is the code I used to test my answer:
import SwiftUI
#main
struct TestApp: App {
#StateObject var myContacts = Contacts()
var body: some Scene {
WindowGroup {
ContentView().environmentObject(myContacts)
}
}
}
struct Contact: Identifiable {
var id = UUID()
var name: String = ""
var email: String = ""
}
class Contacts: ObservableObject {
#Published var contacts: [Contact] = [Contact(name: "name1", email: "email1"), Contact(name: "name2", email: "email2")]
func add(contact: Contact) {
contacts.append(contact)
}
}
struct AddContactView: View {
#Environment(\.presentationMode) private var presentationMode
#EnvironmentObject var myContacts: Contacts
#State var name: String = ""
#State var email: String = ""
var body: some View {
VStack{
HStack{
Text("Name:")
TextField("Enter name", text: $name)
}
.padding(.bottom, 50)
HStack{
Text("Email:")
TextField("Enter email", text: $email)
}
.padding(.bottom, 50)
Button("Submit") {
let contactToAdd = Contact(name: name, email: email)
myContacts.add(contact: contactToAdd)
presentationMode.wrappedValue.dismiss()
}
.frame(width: 80, height: 30, alignment:.center)
.background(Color.blue)
.foregroundColor(.white)
.clipShape(Capsule())
}.padding()
}
}
struct ContentView: View {
#EnvironmentObject var myContacts: Contacts
#State var isAddButtonPressed: Bool = false
var body: some View {
NavigationView {
List {
ForEach(myContacts.contacts) { item in
NavigationLink(destination: AddContactView()) {
Text(item.name)
}
}
}
.navigationBarTitle("Address Book")
.toolbar {
ToolbarItem(placement: .navigationBarLeading){
Button(action: {
isAddButtonPressed.toggle()
}, label: {
NavigationLink(
destination: AddContactView(),
isActive: $isAddButtonPressed,
label: {
Image(systemName: "plus")
})
})
}
ToolbarItem(placement: .navigationBarTrailing){
EditButton()
}
}
}
}
}