WorkflowSavedStateRegistryAggregator

Manages a group of SavedStateRegistryOwners that are all saved to and restored from a single "parent" SavedStateRegistryOwner. SavedStateRegistryOwner is the new androidx alternative to the View.onSaveInstanceState system, and is required by Compose UI.

This class is designed to support a navigation container view that owns a a set of navigation "frames", where a frame is something that can be navigated to/from. A frame loosely consists of a root View and its SavedStateRegistryOwner. For example:

• a back stack container view will own an instance of WorkflowSavedStateRegistryAggregator, and use it to assign a SavedStateRegistryOwner for its top view.

• a container view managing a set of windows will own an instance of WorkflowSavedStateRegistryAggregator, and use it to assign a SavedStateRegistryOwner to each dialog's content view.

Note that a SavedStateRegistryOwner works in parallel to a LifecycleOwner. Use WorkflowLifecycleOwner to ensure one is properly installed.

attachToParentRegistry must be called when the container view is attached to a window, and passed the parent registry. detachFromParentRegistry must be called when the container view is detached.

Call installChildRegistryOwnerOn to put a SavedStateRegistryOwner in place on each managed child view, before it is attached to a window. After that:

• call saveAndPruneChildRegistryOwner if the child is removed from service but may be restored before detachFromParentRegistry is called (as when a back stack pushes and pops)

• call pruneAllChildRegistryOwnersExcept when views are permanently removed from service, taking care to identify the set that remain active

Note that this class does not offer support for the pre-Jetpack View.onSaveInstanceState mechanism. Container views must handle that themselves.