Flip incorrectly when tap the right half page

[daizw]

The right half page will flip DOWN a little when tap the right half page.
Because the CATransform3D is not correct?
To reproduce this bug, just tap the right half page, and look at the up-right corner carefully.
(It would be more easy to see if the up-right corner is not just totally white.)

[daizw]

It seems the solution is pretty simple, just add a '-':

change:
transform.m34 = 1.0f / 2500.0f; (in the else clause)
to:
transform.m34 = -1.0f / 2500.0f;