How do I avoid excess battery usage under iOS4?

I am using the 'location' UIBackgroundMode to receive GPS background updates when the user presses the Home button. As a result, if the app is left in background mode overnight, the battery is consistently dead the next morning. I have told the locationManager to stopUpdatingLocation, but to no effect.

I understand Apple doesn't want developers to use exit - in fact it seems to have little effect on the app other than to take it to the background - but I can't afford to have the battery die if 开发者_如何学运维the user doesn't end the app.

Any suggestions?

Maybe you could register for a local notification that informs the user they should open the app to stop location tracking? It's not very elegant of course, it seems Apple should allow the developer to register for location updates for a specified length of time, maybe you could submit a feature request for that. I think Loopt monitors for 24 hours and then quits, maybe you could research into how they made it stop after 24 hours. I wish I could help more but I haven't messed with the location framework at all.

You could use a timer and/or background task, which would run after a set amount of idle time, and try to turn off the GPS then. So you can still have location tracking in the background of your app, but after 10-20 minutes, it turns off.