iOS 16 NavigationStack binding + navigationDestination behavior (Xcode 14 Beta 1, Swift 5.7) https://twitter.com/inamiy/status/1535861181998862337

iOS16-NavigationStack.swift

import SwiftUI

struct RootStringNavStack: View {
    @State
    var navigationPath: [String] = []

    // For hook-printing.
    var navigationPathBinding: Binding<[String]> {
        .init(
            get: { navigationPath },
            set: {
                print("===> navigationPath", $0)
                navigationPath = $0
            }
        )
    }

    var body: some View {
        NavigationStack(path: navigationPathBinding) {
            StringNavStackChildView(
                title: "String NavStack",
                navigationPath: $navigationPath
            )
            // Top-level navigationDestination only.
            .navigationDestination(for: String.self) { route in
                // TODO: Why `navigationPath.count = 1` is printed after `N >= 2` push transition?
                let _ = print("===> navigationDestination, route = \(route), navigationPath.count = \(navigationPath.count)")
                StringNavStackChildView(title: route, navigationPath: $navigationPath)
            }
        }
    }
}

struct StringNavStackChildView: View {
    let title: String

    @Binding
    var navigationPath: [String]

    init(title: String, navigationPath: Binding<[String]>) {
        self.title = title
        self._navigationPath = navigationPath
    }

    var body: some View {
        List {
            NavigationLink(value: "1") {
                Text("Link 1")
            }
            NavigationLink(value: "2") {
                Text("Link 2")
            }
            NavigationLink(value: "3") {
                Text("Link 3")
            }
        }
        .navigationTitle(title)
        .toolbar {
            Button(action: { navigationPath = [] }) {
                Text("Go Home")
            }
        }
    }
}

/*
// 1. Tap Link 1
===> navigationPath ["1"]
===> navigationDestination, route = 1, navigationPath.count = 1
===> navigationDestination, route = 1, navigationPath.count = 1

// 2. Tap Link 2
===> navigationPath ["1", "2"]
===> navigationDestination, route = 2, navigationPath.count = 2
===> navigationDestination, route = 1, navigationPath.count = 1
===> navigationDestination, route = 2, navigationPath.count = 1

// 3. Tap Link 3
===> navigationPath ["1", "2", "3"]
===> navigationDestination, route = 3, navigationPath.count = 3
===> navigationDestination, route = 1, navigationPath.count = 1
===> navigationDestination, route = 2, navigationPath.count = 1
===> navigationDestination, route = 3, navigationPath.count = 1

// 4. Back button
===> navigationPath ["1", "2"]
===> navigationDestination, route = 1, navigationPath.count = 2
===> navigationDestination, route = 2, navigationPath.count = 2
===> navigationDestination, route = 1, navigationPath.count = 1
===> navigationDestination, route = 2, navigationPath.count = 1

// 5. Back button
===> navigationPath ["1"]
===> navigationDestination, route = 1, navigationPath.count = 1
===> navigationDestination, route = 1, navigationPath.count = 1
*/