How to stop text cursor from jumping to the end in SwiftUI? - swiftui

Question

I'm curious, has anyone seen this before, or do they know how to solve it? I have a situation where editing a textfield that's in a NavigationStack always pops the text cursor to the end of the field on every keystroke. I suspect it has something to do with SwiftUI's management of views and state, but I am not spotting anything unusual that I might be doing, other than the index lookup in the navigationDestination part. I don't understand why that would be a problem.
Here's some pretty minimal code demonstrating the problem (just try correcting the well-known Shakespeare quote):
struct CursorResetting: View {
struct Record: Identifiable {
var string = ""
var id = UUID()
}
#State var path = NavigationPath()
#State private var records = [
Record(string: "To be and not to be"),
Record(string: "That begs the question")
]
var body: some View {
NavigationStack(path: $path) {
Form {
List {
ForEach(records) { record in
NavigationLink(value: record.id) {
Text(record.string)
}
}
}
}
.navigationDestination(for: UUID.self) { id in
let index = records.firstIndex { $0.id == id }
if let index {
Form {
TextField("Value", text: $records[index].string)
}
} else {
Text("Invalid ID")
}
}
}
}
}

Answer 1

This is a known thing, and the reason why you can't use a Binding type with navigationDestination.
Binding triggers the View to redraw and it resets everything in the body including the navigationDestination modifier.
You have to use NavigationLink(destination:, label:)
import SwiftUI
struct CursorResettingView: View {
struct Record: Identifiable {
var string = ""
var id = UUID()
}
#State var path = NavigationPath()
#State private var records = [
Record(string: "To be and not to be"),
Record(string: "That begs the question")
]
var body: some View {
NavigationStack(path: $path) {
Form {
List {
ForEach($records) { $record in
NavigationLink {
Form {
TextField("Value", text: $record.string)
}
} label: {
Text(record.string)
}
}
}
}
.navigationDestination(for: UUID.self) { id in
//Use this for `View`s that don't use `Binding` type as argument.
}
}
}
}
struct CursorResettingView_Previews: PreviewProvider {
static var previews: some View {
CursorResettingView()
}
}
Anything that uses an array's index is generally considered unsafe with SwiftUI so "solutions" that depend on it will be inherently fragile.