SwiftUI & CoreData - ordered list - ios

Question

I am trying to make an ordered list in SwiftUI using CoreData records.
How to print running numbers in such list?
In the following example I have one entity named SomeEntity with a String attribute named title.
import SwiftUI
struct ContentView: View {
var fetchRequest: FetchRequest<SomeEntity>
var items: FetchedResults<SomeEntity> { fetchRequest.wrappedValue }
var body: some View {
NavigationView {
List {
ForEach(items, id: \.self) {item in
NavigationLink(destination: ItemDetailsView(item: item)) {
HStack {
Text("99")
// How to print running number instead of "99" in this ordered list of CoreData records?
// I was thinking about something like this:
// Text(items.id) - but this doesn't work. Is there something similar?
.multilineTextAlignment(.center)
.frame(width: 60)
Text(item.title!)
}
}
}
}
}
}
}

Answer 1

Probably you need something like the following
struct ContentView: View {
var fetchRequest: FetchRequest<SomeEntity>
var items: FetchedResults<SomeEntity> { fetchRequest.wrappedValue }
var body: some View {
NavigationView {
List {
ForEach(Array(items.enumerated()), id: \.element) {(i, item) in
NavigationLink(destination: ItemDetailsView(item: item)) {
HStack {
Text("\(i + 1)")
.multilineTextAlignment(.center)
.frame(width: 60)
Text(item.title!)
}
}
}
}
}
}
}

Answer 2

Based on your comments, this should work: You need to use a different init of ForEach, which takes a Range<Int> as first argument:
ForEach(-items.count..<0, id: \.self) { i in
NavigationLink(destination: ItemDetailsView(item: items[-i])) {
HStack {
Text("\(items[-i].itemName)")
.multiLineTextAlignment(.center)
.frame(width: 60)
Text("\(items[-i].title!)")
}
}
}
Going from -items.count to 0 also ensures the reversed order.

Answer 3

I've tested it and with #FetchRequest this solution seems to be the best.
List {
ForEach(self.contacts.indices, id: \.self) { i in
Button(action: {
self.selectedId = self.contacts[i].id!
}) {
ContactRow(contact: self.contacts[i])
.equatable()
.background(Color.white.opacity(0.01))
}
.buttonStyle(ListButtonStyle())
.frame(height: 64)
.listRowBackground( (i%2 == 0) ? Color("DarkRowBackground") : .white)
.listRowInsets(EdgeInsets(top: 0, leading: 0, bottom: 0, trailing: 0))
}
}
I've tested also solution with Array(self.contacts.enumerated()) but it doesn't work as well. If you there is small number of records it can be ok but for large number of records it is suboptimal.
If you use
request.fetchBatchSize = 10
to load records (entities) in batches while scrolling the list enumerated() doesn't work executes all needed SELECT ... LIMIT 10 requests at once
.indices makes it possible to fetch additional items while scrolling.