Dynamic cell height in UICollectionViewCompositionalLayout.swift

  let layout = UICollectionViewCompositionalLayout(sectionProvider: {
    (sectionIndex: Int, layoutEnvironment: NSCollectionLayoutEnvironment) -> NSCollectionLayoutSection? in

    let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
                                          heightDimension: .estimated(30))
    let item = NSCollectionLayoutItem(layoutSize: itemSize)

    let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
                                           heightDimension: .estimated(30))

    let group = NSCollectionLayoutGroup.horizontal(
      layoutSize: groupSize,
      subitem: item,
      count: 1
    )
    
    let section = NSCollectionLayoutSection(group: group)
    section.interGroupSpacing = 16

    return section
  })