SwiftUI tab bar view that respects navigation stacks when tabs are switched (unlike the TabView implementation)

0_UIKitTabView.swift

import SwiftUI

/// An iOS style TabView that doesn't reset it's childrens navigation stacks when tabs are switched.
struct UIKitTabView: View {
    var viewControllers: [UIHostingController<AnyView>]
    @State var selectedIndex: Int = 0
    
    init(_ views: [Tab]) {
        self.viewControllers = views.map {
            let host = UIHostingController(rootView: $0.view)
            host.tabBarItem = $0.barItem
            return host
        }
    }
    
    var body: some View {
        TabBarController(controllers: viewControllers, selectedIndex: $selectedIndex)
            .edgesIgnoringSafeArea(.all)
    }
    
    struct Tab {
        var view: AnyView
        var barItem: UITabBarItem
        
        init<V: View>(view: V, barItem: UITabBarItem) {
            self.view = AnyView(view)
            self.barItem = barItem
        }
        
        // convenience
        init<V: View>(view: V, title: String?, image: String? = nil, systemImage: String? = nil, selectedImage: String? = nil) {
            let image = image != nil ? UIImage(named: image!) : systemImage != nil ? UIImage(systemName: systemImage!) : nil
            let selectedImage = selectedImage != nil ? UIImage(named: selectedImage!) : nil
            let barItem = UITabBarItem(title: title, image: image, selectedImage: selectedImage)
            self.init(view: view, barItem: barItem)
        }
    }
}

1_TabBarController.swift

import SwiftUI
import UIKit

struct TabBarController: UIViewControllerRepresentable {
    var controllers: [UIViewController]
    @Binding var selectedIndex: Int

    func makeUIViewController(context: Context) -> UITabBarController {
        let tabBarController = UITabBarController()
        tabBarController.viewControllers = controllers
        tabBarController.delegate = context.coordinator
        tabBarController.selectedIndex = 0
        return tabBarController
    }

    func updateUIViewController(_ tabBarController: UITabBarController, context: Context) {
        tabBarController.selectedIndex = selectedIndex
    }
    
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    class Coordinator: NSObject, UITabBarControllerDelegate {
        var parent: TabBarController

        init(_ tabBarController: TabBarController) {
            self.parent = tabBarController
        }
        
        func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
            if parent.selectedIndex == tabBarController.selectedIndex,
                let selectedView = parent.controllers[tabBarController.selectedIndex].viewIfLoaded,
                let scrollView = selectedView.subviews(ofType: UIScrollView.self).first,
                scrollView.scrollsToTop == true {
                scrollView.setContentOffset(CGPoint(x: 0, y: -scrollView.adjustedContentInset.top), animated: true)
            } else {
                parent.selectedIndex = tabBarController.selectedIndex
            }
        }
    }
}

2_Example.swift

struct ExampleView: View {
    @State var text: String = ""
    
    var body: some View {
        UIKitTabView([
            UIKitTabView.Tab(view: NavView(), title: "First"),
            UIKitTabView.Tab(view: Text("Second View"), title: "Second", systemImage: "star.fill")
        ])
    }
}

struct NavView: View {
    var body: some View {
        NavigationView {
            VStack {
                NavigationLink(destination: Text("This page stays when you switch back and forth between tabs (as expected on iOS)")) {
                    Text("Go to detail")
                }
            }
        }
    }
}