Replicating the underlying code of the fullScreenCover view modifier to use UIKit presentation

Question

The fullScreenCover view modifier doesn't seem to really "modify" the view, it just presents a view on top. So I'm wondering what the underlying code looks like. This is the function:

func fullScreenCover<Content>(isPresented: Binding<Bool>, onDismiss: (() -> Void)? = nil, content: @escaping () -> Content) -> some View where Content : View

I want to try making a similar custom view modifier that takes an isPresented binding and runs some UIKit code to present a view.

Currently I am listening to a @Published value and then presenting the view like this:

.onReceive(controller.$showMyView) { showingMyView in
   if showingMyView {
     MyUIKitComponent.present(
       onDismiss: {
         controller.showMyView = false
         // Do some other stuff here
       }
     )
   }
 }

But I'd like to turn it into a view modifier like this:

.showMyView(
  isPresented: $controller.showMyView,
  onDismiss: {
     // Do some other stuff here
  }
)

How can I do this?