MovieViewController.swift

fileprivate func createOnGoingMovieSection() -> NSCollectionLayoutSection {
      let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0), heightDimension: .fractionalWidth(2/3))
      let item = NSCollectionLayoutItem(layoutSize: itemSize)
      let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0), heightDimension: .fractionalWidth(1.0))
      let group = NSCollectionLayoutGroup.vertical(layoutSize: groupSize, subitem: item, count: 3)
      group.contentInsets = .init(top: 5, leading: 0, bottom: 5, trailing: 20)
      
      let headerSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
      heightDimension: .estimated(44))
      let sectionHeader = NSCollectionLayoutBoundarySupplementaryItem(layoutSize: headerSize, elementKind: MovieViewController.sectionHeaderElementKind, alignment: .top)
      
      let section = NSCollectionLayoutSection(group: group)
      section.orthogonalScrollingBehavior = .groupPaging
      section.boundarySupplementaryItems = [sectionHeader]
      return section
}