Changes

In the case of a constraint that references a single view, the constraint must be added to the immediate parent of the view. When a constraint references two views, the constraint must be applied to the closest ancestor of the two views. Consider, for the purposes of an example, the view hierarchy illustrated in Figure 20-1.

[[Image:ios_6_autolayout_view_heirarchy.png|iOS 6 Auto Layout View Hierarchy Diagram]]