I heard somewhere long ago that after you lock your iOS screen, it will go to a deep sleep mode after a certain period of time. In this mode, apps can no longer do anything or triggering an NSTimer. Is there any specific time duration before entering this deep sleep mode?
NOTE: guys, please don't just answer with links. Extract some information you found before putting them in here. It won't be hard if you know the answer is in those links, right?