Hardly undocumented! https://developer.android.com/guide/components/activities/process-lifecycle https://developer.android.com/guide/components/activities/pr..

Hardly undocumented! https://developer.android.com/guide/components/activities/process-lifecycle https://developer.android.com/guide/components/activities/pr... The expectation in mobile environments is that you store whatever information you need to resume from cold in response to the app leaving the foreground, since the OS may kill it with little further warning at any time thereafter. This recommendation occurs prominently in the lifecycle docs for both iOS and Android.