Some New features in iOS 6

1.  Constraints...
     Constraints used for alinement you can turn it on of by clicking  Use Autolayout in File inspector
     By default, Auto Layout is switched on for user interface.

                             

2. UICollectionView

    As per Apple Class reference 

     The UICollectionView class manages an ordered collection of data items and presents them using customizable layouts. Collection views provide the same general function as table views except that a collection view is able to support more than just single-column layouts

     Now you can easily create grid like Photos app, and customize it like UITableView

These are dataSource methods for UICollectionView

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath

as you can see all are same as UITableView dataSource methods, now you have to create a UICollectionViewCell class , Customize it according to your need and return it in 

 - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath

Here is the YouTube Video For this.