How detect iphone battery level in application running in background?

I am developing an iphone application which includes battery level tracking.开发者_开发技巧 The main requirement of my application is to run application in background and comes on foreground when battery level reaches to low. I knew battery level tracking in iphone is not a big task but how can i do it from the background? can it be possible to do this type of work in background. Any idea will appreciable.

Thanks in advance.

This can be done only on devices which support multitasking , You can look for more details here..

http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/BackgroundExecution/BackgroundExecution.html

The page does give some info regarding performing tasks in background..