If you know what view controller you are working with, you can get the rect within the window.
CGRect rectInWindow = [self.view convertRect:self.view.bounds toView:self.view.window];
if rectInWindow.orig.y == 0
and rectInWindow.size.height == self.view.window.bounds.size.height
, then you are extended.
NOTE: This only works after -viewDidAppear:
.