How does FragmentManager determine when to call onSavedStateHandle?

FragmentManager calls onSavedStateHandle when the fragment's state is saved, for example during a configuration change (screen rotation) or when the app goes into the background. This allows data to be saved for later restoration.

The mechanism works as follows: when onSaveInstanceState is called on a fragment, FragmentManager saves the state, including data from SavedStateHandle. When the fragment is recreated, this data can be retrieved from SavedStateHandle to restore the UI state or other important parameters.

Thus, FragmentManager determines the need to call onSavedStateHandle based on the fragment's lifecycle and events related to saving the application's state.