WhileUiSubscribed

A SharingStarted meant to be used with a StateFlow to expose data to the UI.

When the UI stops observing, upstream flows stay active for some time to allow the system to come back from a short-lived configuration change (such as rotations). If the UI stops observing for longer, the cache is kept but the upstream flows are stopped. When the UI comes back, the latest value is replayed and the upstream flows are executed again. This is done to save resources when the app is in the background but let users switch between apps quickly.