Complete list is recreates all views even if just one item has changed - ios

Question

I have a very simple schoolbook example of a SwiftUI List view that renders items from data in an array. Data in the array is Identifiable. But, when I change the the data in the array, add or remove a item then all rows in the list view are recreated. Is that correct? My understanding was that Identifiable should make sure that only the view in the list that are changed are recreated.
My list is inside a navigation view and each row links to a detail view. The problem is that since all items in the list are removed and recreated every time the data is changed then if that that happens when Im in a detail view (it's triggered by a notification) then Im thrown out back to the list.
What am I missing?
Edit: Added code example
This is my data struct:
struct Item: Identifiable {
let id: UUID
let name: String
init(name: String) {
self.id = UUID()
self.name = name
}
}
This is my ItemView
struct ItemView: View {
var item: Item
init(item: Item) {
self.item = item
print("ItemView created \(self.item.id)")
}
var body: some View {
Text(self.item.name)
}
}
An finally my list view:
struct KeyList: View {
#State var items = [Item(name: "123"), Item(name: "456"), Item(name: "789")]
var body: some View {
VStack {
List(self.items) { item in
ItemView(item: item)
}
Button(action: {
self.items.append(Item(name: "New"))
}) {
Text("Add")
}
}
}
}
When I press add it will print "ItemView created" 4 times. My understanding is that it should only do it 1 time?

Answer 1

Here is an example of how this could work. Tested and working on iOS 13.5
The List doesn't get recreated again when only one item is being removed. So this was accomplished.
About the poping of the View this has already been answered here:
SwiftUI ForEach refresh makes view pop
I have here a small workaround for this problem. Add the items you want to remove to an array. Then when going back, remove these items (Which will make the view pop) or go back programmatically and nothing gets removed
struct ContentView: View {
#State var text:Array<String> = ["a", "b", "c"]
var body: some View {
NavigationView() {
VStack() {
List() {
ForEach(self.text, id: \.self){ item in
NavigationLink(destination: SecondView(textItem: item, text: self.$text)) {
Text(item)
}
}
}
Button(action: {
self.text.remove(at: 0)
}){
Text("Remove \(self.text[0])")
}
}
}
}
}
struct SecondView: View {
#State var textItem: String
#Binding var text: Array<String>
#State var tmpArray: Array<String> = []
#Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
var body: some View {
VStack() {
Text(self.textItem)
Button(action: {
//Append to a tmp array which will later be used to determine what to remove
self.tmpArray.append(self.text[0])
}){
Text("Remove \(self.text[0])")
}
Button(action: {
if self.tmpArray.count > 0 {
//remove your stuff which will automatically pop the view
self.text.remove(at: 0)
} else {
// programmatically go back as nothing has been deleted
self.presentationMode.wrappedValue.dismiss()
}
}){
Text("Go Back")
}
}
}
}