pstCollectionView.contentSize.height == 431, while uiCollectionView.contentSize.height == 162.5. See http://i6.minus.com/jqrf8if9AEwDl.png for result.

PSTCollectionView.contentSize

iPhone 6.0 Simulator

(lldb) po self.collectionView
(PSTCollectionView *) $1 = 0x12a13a00 <UICollectionView: 0x12a13a00; frame = (0 0; 320 431); clipsToBounds = YES; autoresize = W+H; gestureRecognizers = <NSArray: 0x1216de90>; layer = <CALayer: 0x1216db60>; contentOffset: {0, -64}> collection view layout: <PSUICollectionViewFlowLayout_: 0x12173d00>
(lldb) p (UIEdgeInsets) [self.collectionView contentInset]
(UIEdgeInsets) $2 = {
  (CGFloat) top = 64
  (CGFloat) left = 0
  (CGFloat) bottom = 0
  (CGFloat) right = 0
}
(lldb) p (CGSize) [self.collectionView contentSize]
(CGSize) $3 = (width=320, height=162.5)


iPhone 5.1 Simulator

(lldb) po self.collectionView
(PSTCollectionView *) $1 = 0x0abfae00 <PSTCollectionView: 0xabfae00; baseClass = UIScrollView; frame = (0 0; 320 431); clipsToBounds = YES; autoresize = W+H; layer = <CALayer: 0x8a7ab80>; contentOffset: {0, 0}> collection view layout: <PSUICollectionViewFlowLayout_: 0x8a99e60>
(lldb) p (UIEdgeInsets) [self.collectionView contentInset]
(UIEdgeInsets) $2 = {
  (CGFloat) top = 64
  (CGFloat) left = 0
  (CGFloat) bottom = 0
  (CGFloat) right = 0
}
(lldb) p (CGSize) [self.collectionView contentSize]
(CGSize) $3 = (width=310, height=431)