With the release of iOS 6, we observed a curious new bug in one of our iPhone apps: after applying a 3D-rotation to a view, views beneath the rotated view were rendered out of order: that is, a view A under a rotated view B will be drawn above view B.
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http://tech.xtremelabs.com/ios-6-rendering-bug-3d-rotation-causes-layers-to-render-without-respect-for-view-hierarchy/