permanent-parts.md

Permanent parts

Not every child you want to add needs the dynamism of the back stack though – some should always be added and never removed.

To hold routing configurations that should always be on screen (e.g. a Menu), you can use the Permanent routing source, which takes an Iterable of configurations:

class Permanent<C : Parcelable>(
    permanents: Iterable<C>
) : RoutingSource<C>

You can also use this helper methods to create one:

fun <C : Parcelable> permanent(vararg permanents: C) =
    Permanent(permanents.toSet())

And you can use operator overload to combine it with your back stack before passing it to your Router:

routingSource = backStack + permanent(Menu)

In the above screen, the bottom navigation menu is a permanent part that allows changing the content of the sibling view.