How to update variable in List For Each - swiftui

Question

struct NotesView: View {
#State var notesArray = [Note]()
public var deleteid: String
var body: some View {
List{
ForEach(notesArray, id: \._id) { notesArray in
NavigationLink(destination: AddNotesView(addNotesViewIdentifier: "updateNote", id: notesArray._id, title: notesArray.title, note: notesArray.note, noteDate: notesArray.date)){
HStack {
Text(notesArray.title)
deleteid = notesArray._id //ERROR - Cannot assign to property: 'self' is immutable
}
}
}
.onDelete(perform: deleteNoteAtIndex)
}
}
func deleteNoteAtIndex(at offsets: IndexSet){ APIFunctions.functions.DeleteNote(id: _id) }
I was expecting the variable "deleteid" to update.
I assumed you can modify any variable by calling that variable and set it equal to a new value.
Like this
First declare variable:
var deleteid: String
next modify variables string valve
deleteid = notesArray._id

Answer 1

A couple of things:
This isn't directly related to your question, but may help you navigation your own code better... When you create a ForEach view to iterate over an array, you should use a different name for the value that represents each element in the iteration. Here, you're using the name notesArray for your array of notes, then creating a second local variable called notesArray for the loop. That variable inside the block will be an instance of Note, so I'd name it note, e.g.:
ForEach(notesArray, id: \._id) { note in
NavigationLink(destination: AddNotesView(addNotesViewIdentifier: note._id, // etc
}
If you want variables to be modifiable inside views, they should be #State variables. This is important due to the way Swift struct lifecycles work, and how the SwiftUI rendering system loads and reloads structs as it works out what has changed.
I'm not entirely sure what deleteid is supposed to represent here, and it's possible you don't need it at all. If you're using the onDelete modifier to implement SwiftUI's native swipe-to-delete system, SwiftUI will give you an IndexSet, which is a collection (usually of just one) of the positions of the item(s) to delete in the array.
From there, you can find the item(s) at each index and then either remove them, or lookup some other value (e.g., their _id attribute) and do some other operation on them.
So the method you might call in onDelete could look something like:
func deleteNoteAtIndex(offsets: IndexSet) {
// get the array objects that the offsets point to
let notes = offsets.map { noteArray[$0] }
for note in notes {
APIFunctions.functions.deleteNote(id: note._id)
}
}