CollectionView3.swift

/*The trick is to adopt the protocol UICollectionViewDelegateFlowLayout
and implement the following method*/

//UICollectionViewDelegateFlowLayout method
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, 
                    sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize{
    //specify height as per your requirement
    return CGSize(width: collectionView.bounds.width, height: 120)
}