Hi there,
I’m not sure I understand exactly what you’re trying to do. On iOS, how else would someone leave the app except by pressing the home button? The only other ways I can think of would be (a) actions initiates by your app that take the user out of the app, like logging into facebook, opening a URL, etc., and (b) actions from outside the app that force the app to suspend, like receiving a phone call, activating Siri, etc. For (a), you could set a flag before the action is taken so that, when the app resumes, you check the flag to tell whether the suspension was caused by your app or by the user. That would distinguish (a) from (b). But within (b), I don’t see a way to separate out the case where the user presses the home button from the other reasons the app might get suspended.
More importantly, though, I wonder why you’re trying to accomplish this? Most users expect an app to simply resume where they left it. They might be annoyed at having to view an opening sequence again (unless there’s some legitimate reason for it).