One of the tricker parts of Android development is handling process restoration. Android will kill processes in the background to free memory and restore them with savedInstanceState in a new process. This is normally cumbersome and error-prone for Android developers if they are even aware that this exists at all.
This lesson will walk through what Android does to your app in the background and how
@PersistState makes it easier to restore user state even when returning to your app in a new process.