问题
How to calculate engagement time whenever my app is in background. User engagement (firebase automatically collected event) calculate periodically, while the app is in the foreground. But how to add the time in user engagement when my app is in back ground. Or i need to instrument other event.. Any Idea????
回答1:
When your app is in the background, the user isn't "engaged" with it at all. With newer versions of Android, the OS may immediately kill your backgrounded app at any time without warning, so it's even more difficult to calculate a meaningful metric for background time. It seems to me that background time is a mostly meaningless metric, in terms of analytics. Background time has a use in Firebase Performance Monitoring, but app performance in this respect isn't the same as analytics.
来源：https://stackoverflow.com/questions/52307287/engagement-time-calculation-when-app-is-in-background