iphone: Custom view layout during an active call status bar

I have a custom view, where in I draw some numbers inside squares. All this is done using Quartz programming. During an active call, the status bar gets displayed at the top and my view shifts to the bottom. Until now, it's fine. But when I tried to redraw the view based on touch events on the squares, the position of the squares is messed up and gets drawn in a different position. I know that I have to dynamically derive the coordinates of these squares instead of having a fixed coordinates. But how do I know that the status bar is being displayed or shrinked to make appropriate view changes?

I tried to handle the event using application:willChangeStatusBarFram开发者_开发百科e:, but it never got invoked. How to catch the status bar status?

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