Say someone is using my app, and they get to a critical state, ex they are entering some data. Say at that same time the phone rings so they answer the phone, forcing my app into the background. After the phone call ends, if they click on the icon of my app, I want it to bring them back into the activity they left. How do I do that?
Edit
One thing I forgot to clarify (apologies) is that the activity the user left is not the main activity. I need to re-open the app in an activity that is normally not the main entry point.