I've written an app which uses a timer. Never mind the details but every second the app beeps. Works fine. The iPhone (at least the display) goes to "sleep" after some period of time, 30 seconds maybe. When my app is running, the display sleeps, but my app keeps beeping away. Is there a way to find out when the iPhone has gone to sleep so I can stop processing? (When I click the Home button to wake the iPhone, the app quits properly. I'd like it to at least halt/pause or even quit on this "sleep" event.) Thanks!