Update UIKit View From Hosted SwiftUI Selection - ios

Question

Have a UIKit Navigation Controller that is the root view controller in the hierarchy of the storyboards. One of the button items navigates to a UIHostedViewController that produces a SwiftUI View. That SwiftUI View is in and of itself a Tab View with tabs - and all of it works fine.
One of the crux of our development is displaying large data models for the user, and we could regain a bit of screen real estate if we utilize the Navigation bar of the UIKit Navigation.
A defining attribute of our individual views is the color coding of the header and footer, we have been able to change these colors easily as the SwiftUI Tab View just calls different views with different modifiers.
What we would like to do is have the selection of the SwiftUI Tab View set a shared property with the UIKit view that would then change the navigation bar color - however the way we setup a bound variable and reload the NavigationBar setup with a didSet on that variable does not seem to be working.
The code is almost exactly as follows, less a couple of views.
class SomeViewController: UIHostingController< MySwiftUITabView > {
var headerColor: Binding<UIColor> = .constant(UIColor.blue) {
didSet {
DispatchQueue.main.async(qos: .userInteractive) {
self.setupUI()
}
}
}
var defaultColor: UIColor!
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder, rootView: MySwiftUITabView(headerColor: headerColor))
}
override func viewDidLoad() {
super.viewDidLoad()
defaultColor = self.navigationController?.navigationBar.backgroundColor
setupUI()
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
teardownUI()
}
func setupUI() {
if let naviController = self.navigationController {
let newNavBarAppearance = UINavigationBarAppearance()
newNavBarAppearance.backgroundColor = headerColor.wrappedValue
naviController.navigationBar.scrollEdgeAppearance = newNavBarAppearance
naviController.navigationBar.compactAppearance = newNavBarAppearance
naviController.navigationBar.standardAppearance = newNavBarAppearance
}
}
func teardownUI() {
if let naviController = self.navigationController {
let oldNavBarAppearance = UINavigationBarAppearance()
oldNavBarAppearance.backgroundColor = defaultColor
naviController.navigationBar.scrollEdgeAppearance = oldNavBarAppearance
naviController.navigationBar.compactAppearance = oldNavBarAppearance
naviController.navigationBar.standardAppearance = oldNavBarAppearance
}
}
}
And the SwiftUI Tab View:
struct MySwiftUITabView: View {
#Binding var headerColor: UIColor
var body: some View {
TabView(selection: $selectedTab){
TestView()
.tag(0)
.onAppear {
headerColor = .orange
}
.tabItem {
Label("Test", image: "circle.fill")
}
TestView()
.tag(1)
.onAppear {
headerColor = .red
}
.tabItem {
Label("Test", image: "square.fill")
}
}
.accentColor(.white)
}
}
Would a callback be more appropriate for this? We wrapped the didSet function call in a DispatchGroup as a final attempt since it is updating the UI, but the was not effective still for what we are looking for.
In this example, the navigation bar remains the same color as the original set value (.blue) and never gets updated to the color set to the binding by the .onAppear of the swiftUI tab items.
Any help would be greatly appreciated as always!