AutoLayout

Autolayout, available starting with OS X v10.7 Lion, uses relationships called constraints to govern the layout of objects in the user interface. This feature is a complete replacement for the autoresizing mask. As you make changes to any view or control in Interface Builder (move it around, resize it, change an attribute, add a subview, and so forth), Interface Builder automatically adds and removes constraints based on the new layout. When you enable this feature, Interface Builder shows the constraints as you work.

When you enable Autolayout, Xcode updates your build settings, if necessary, to ensure your deployment target is OS X v10.7 or greater. For nib files in projects that had been targeted for OS X v10.6 or earlier, Interface Builder adds constraints to your nib files automatically when you enable Autolayout.



UIViewAutoresizing ：
    Specifies how a view is automatically resized.

enum {
   UIViewAutoresizingNone                 = 0,
   UIViewAutoresizingFlexibleLeftMargin   = 1 << 0,
   UIViewAutoresizingFlexibleWidth        = 1 << 1,
   UIViewAutoresizingFlexibleRightMargin  = 1 << 2,
   UIViewAutoresizingFlexibleTopMargin    = 1 << 3,
   UIViewAutoresizingFlexibleHeight       = 1 << 4,
   UIViewAutoresizingFlexibleBottomMargin = 1 << 5
};
typedef NSUInteger UIViewAutoresizing;

UIViewAnimationTransition
Specifies a transition to apply to a view in an animation block.

typedef enum {
   UIViewAnimationTransitionNone,
   UIViewAnimationTransitionFlipFromLeft,
   UIViewAnimationTransitionFlipFromRight,
   UIViewAnimationTransitionCurlUp,
   UIViewAnimationTransitionCurlDown,
} UIViewAnimationTransition;