Keep connection to host opened even when the iPhone/Ipad screen is lock or when moves to another app

Our iPhone app allows users to share files on a host computer
display while in a meeting.  To keep files
secure, once the meeting ends, or if the user decides to unshare
their files we remove it from the screen and any delete any temporary
copies.  To be secure and ensure the user has not closed the iPhone app or
has left the meeting, the host computer  send a heartbeat signal to the
iPhone app.  This works very well, except when the user locks the screen
or moves to another app (like email).  When our app is put in the
background it cannot respond to the host computer events and the host assumes
the user has purposely left the meeting.  It will then close there files
and delete them.  This is a very poor user experience, as a user might
have simply been checking the email or maybe looking for another file.
 

We need for our app to stay active in the background so that is
can respond to host computer messages.

 

We tried to use audio background app, but we have been rejected
many times by the apple store.

 

Can you please give us advise on how we can keep our app active in
the background that would be acceptable to the apple store?
Keep connection to host opened even when the iPhone/Ipad screen is lock or when moves to another app
 
 
Q