RFQuiltLayout
A UICollectionViewLayout subclass to put items in a quilting pattern, with PSTCollectionView support in iOS5
RFQuiltLayout *layout = (RFQuiltLayout*)self.collectionView.collectionViewLayout;
layout.blockPixels=CGSizeMake(256, 256);
layout.direction=UICollectionViewScrollDirectionVertical;
layout.predrawEverything=YES;
layout.delegate=self;
[layout setMinimumInteritemSpacing:5];