How should an app-wide blocking state (e.g. a mandatory update gate, or a security lockout) be propagated across all open windows on iPhone Duo?

My app has a blocking condition that's meant to halt the entire app, not just the current screen — for example a mandatory-update check that must pass before any use, or a security check that should lock the whole app if it fails. Previously, with a single window, blocking that one window effectively blocked the whole app.

With multi-window now standard on iPhone Duo, if this condition is detected while running in one scene, does it need to be manually propagated to every other currently-connected scene (e.g. via NotificationCenter or shared app-level state each scene observes), or does Apple provide a built-in mechanism for "this app-wide state changed, all active scenes should react" that I should be using instead of rolling my own?