swift-calendar-data.swift

func numberOfSections(in collectionView: UICollectionView) -> Int {
  return calendarRange.count
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
  return calendarRange[section].daysInMonth
}

func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
  switch kind {
  case UICollectionView.elementKindSectionHeader:

    let section = calendarRange[indexPath.section]
    let date = CalendarManager.getDate(year: section.year, month: section.month)
    let header = CalendarHeader.dequeue(from: collectionView, at: indexPath, forDate: date)

    return header
  default:
    fatalError("Invalid element type")
  }
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
  let section = calendarRange[indexPath.section]
  let daysInSection = section.daysInMonth
  let day = daysInSection - indexPath.item

  let cell = CalendarCell.dequeue(from: collectionView, at: indexPath, forDay: day)

  return cell
}