SwiftUI pass binding through NavigationStack enum - swiftui

Question

I am attempting to pass a Binding through my NavigationStack enum into my View. I'm not sure if I can pass Binding into an enum, if I cannot then how should I go about this. Thanks in advance!
#available(iOS 16.0, *)
enum Route: Hashable, Equatable {
//ERROR HERE: Not sure how to get Binding in enum or if possible
case gotoBView(input: Binding<String>)
#ViewBuilder
func view(_ path: Binding<NavigationPath>) -> some View{
switch self {
case .gotoBView(let input): BView1(bvar: input)
}
}
var isEmpty: Bool {
return false
}
}
//START VIEW
#available(iOS 16.0, *)
struct ContentView25: View {
#State var input = "Hello"
#State var path: NavigationPath = .init()
var body: some View {
NavigationStack(path: $path){
NavigationLink(value: Route.gotoBView(input: $input), label: {Text("Go To A")})
.navigationDestination(for: Route.self){ route in
route.view($path)
}
}
}
}
//View to navigate to with binding
#available(iOS 16.0, *)
struct BView1: View {
#Binding var bvar: String
var body: some View {
Text(bvar)
}
}

Answer 1

Here is a workaround, in previous iOS versions this has dismissed the NavigationLink, In iOS 16.2 it does not behave this way, I would do extensive testing before using this in a production app.
import SwiftUI
#available(iOS 16.0, *)
enum Route: Hashable, Equatable {
case gotoBView(input: Binding<String>)
#ViewBuilder
func view(_ path: Binding<NavigationPath>) -> some View{
switch self {
case .gotoBView(let input): BView1(bvar: input)
}
}
//Create a custom implementation of Hashable that ignores Binding
func hash(into hasher: inout Hasher) {
switch self {
case .gotoBView(let input):
hasher.combine(input.wrappedValue)
}
}
//Create a custom implementation of Equatable that ignores Binding
static func == (lhs: Route, rhs: Route) -> Bool {
return lhs.hashValue == rhs.hashValue
}
}
SwiftUI is all about identity and NavigationPath uses Hashable and Equatable to function. This bypasses SwiftUI's implementation.

Answer 2

With the stack, you don't need an enum, you can have multiple navigationDestination for each value type. To use it with a binding you can do it the old way, with a func that looks it up by ID, like how we did it before ForEach supported bindings, e.g.
struct NumberItem: Identifiable {
let id = UUID()
var number: Int
var text = ""
}
struct ContentView: View {
#State var numberItems = [NumberItem(number: 1), NumberItem(number: 2), NumberItem(number: 3), NumberItem(number: 4), NumberItem(number: 5)]
var body: some View {
NavigationStack {
List {
ForEach(numberItems) { numberItem in
NavigationLink(value: numberItem.id) {
Text("\(numberItem.number)")
}
}
}
.navigationDestination(for: NumberItem.ID.self) { numberItemID in
ChildDetailView(numberItems: $numberItems, numberItemID: numberItemID)
}
//.navigationDestination(for: AnotherItem.ID.self) { anotherItemID in
// ...
//}
}
}
}
// this wrapper View was originally needed to make bindings in
// navigationDestinations work at all, now its needed to fix a bug
// with the cursor jumping to the end of a text field which is
// using the binding.
struct ChildDetailView: View {
#Binding var numberItems: [NumberItem]
let numberItemID: UUID
var body: some View {
ChildDetailView2(numberItem: binding(for: numberItemID))
}
private func binding(for numberItemID: UUID) -> Binding<NumberItem> {
guard let index = numberItems.firstIndex(where: { $0.id == numberItemID }) else {
fatalError("Can't find item in array")
}
return $numberItems[index]
}
}
struct ChildDetailView2: View {
#Binding var numberItem: NumberItem
var body: some View {
VStack {
Text("\(numberItem.number)")
TextField("Test", text: $numberItem.text) // cursor jumps to the end if not wrapped in an extra View like this one is.
Button {
numberItem.number += 10
} label: {
Text("Add 10")
}
}
.navigationTitle("Detail")
}
}