DeveloperMaris/experiment-uinavigationcontroller-environment-object

An experiment code demonstrating a way how to inject an environment object if codebase is using UINavigationController

Experiment of providing an environment object while using UINavigationController (iOS)

SwiftUI situation

If the application uses SwiftUI navigation, then the EnvironmentObject needs to be provided for the navigation view, so that the EnvironmentObject would automatically be available to all pushed views in the navigation stack:

NavigationStack {
    ContentView()
}
.environmentObject(profile) // where Profile is an ObservableObject.

UIKit situation

If the application uses UIKit navigation, then the EnvironmentObject needs to be provided for the view, because we can't provide it for the UINavigationController:

let view = ContentView()
    .environmentObject(profile) // where Profile is an ObservableObject.
    
let controller = UINavigationController(rootViewController: UIHostingController(rootView: view))
// show controller on the screen

This approach comes with a downside, that the EnvironmentObject will be available only in the ContentView, but not in the other pushed views in the navigation stack. You will need manually provide the EnvironmentObject to each of the pushed views in the navigation stack.

UIKit solution

To solve this issue by wrapping the UINavigationController in a UIViewControllerRepresentable struct. Provide an EnvironmentObject to this struct and place it into the UIHostingController.

struct NavigationControllerView<ViewController: UIViewController>: UIViewControllerRepresentable {
    var content: () -> ViewController
    
    func makeUIViewController(context: Context) -> UINavigationController {
        UINavigationController(rootViewController: content())
    }

    func updateUIViewController(_ uiViewController: UINavigationController, context: Context) {
        // modify navigation controller
    }
}

...

let view = NavigationControllerView { 
    UIHostingController(rootView: ContentView())
}
.environmentObject(profile) // where Profile is an ObservableObject.
    
let controller = UIHostingController(rootView: view)
// show controller on the screen

In the end we get a view hierarchy like this:

UIHostingController 
  > UINavigationController as UIViewRepresentable with environmentObject() 
    > UIHostingController 
      > some View

Requirements

• Xcode 14.1.0