I made a UICollectionView with a vertical scroll.
The width of the cell is more than than the screen width, so I created a customFlowLayout
I'm not sure I've understood your problem.
But if you have made a custom layout, make sure you have implemented :
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath;
and that your layout attributes frame and size are set with correct values for your "large cell" index path.
Also make sure you have implemented :
- (CGSize) collectionViewContentSize;
This method returns the contentSize of the collection View. If contentSize.width > youAppFrame.width you should have horizontal scrolling. Same for height and vertical scrolling.
Also make sure your collectionView allows scrolling and that your layout is prepared correctly using :
- (void)prepareLayout
By the way, for your layout have you overloaded UICollectionViewLayout or UICollectionViewFlowLayout ?