How to ignore a local notification when iPhone is locked?

I am implementing a voip app for iphone. Upon receiving an incoming call, the app shows a local notification with two buttons : close and answer. If the user clicks on answer, the app shows in foreground and the call is answered, and if she clicks on 'close', the call is ignored.

The problem, however, is that when iphone is locked, there is no 'close' button, only a slider for which sliding from left to right means 'answer'. Hence there is no way to ignore the call. Is there a way to solve this? The only solution I found so far is to show anot开发者_如何学Pythonher notification for the user to answer or reject, but that seems inconvenient to use.

Re-locking the screen (using the sleep/lock button) usually constitutes ignoring a notification. Have you tested whether your app receives some kind of message when that happens?