I have application which is working best with Wifi,3G..
Now what i want is i want to check in background if Airplane mode is going to be on at any moment and i want to popup alert saying "Airplane mode is On."
Thanks in advance.
You can think different approach, check your mobile Network availability rather than the Airplane mode and Show a Generic Alert There is no network Available for example.
Check This link iphone-sdk-testing-network-reachability
Good luck
This is practically impossible unless the user does it within a 10 minute time frame of your application entering background mode.
来源：https://stackoverflow.com/questions/5814947/how-to-check-airplane-mode-in-background-in-iphone