Extensions to help on UICollectionView implementation

UICollectionView+Extensions.swift

import UIKit

extension UICollectionView {

  /// Register cell
  /// - Parameter cell: Cell to be registered
  public func register(_ cell: UICollectionViewCell.Type) {
    let nib = UINib(nibName: cell.identifier, bundle: nil)
    register(nib, forCellWithReuseIdentifier: cell.identifier)
  }

  /// Register header
  /// - Parameter reusableView: Collection header view to be registered
  public func registerHeader(_ reusableView: UICollectionReusableView.Type) {
    let nib = UINib(nibName: reusableView.identifier, bundle: nil)
    register(
      nib,
      forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader,
      withReuseIdentifier: reusableView.identifier
    )
  }

  /// Register footer
  /// - Parameter reusableView: Collection footer view to be registered
  public func registerFooter(_ reusableView: UICollectionReusableView.Type) {
    let nib = UINib(nibName: reusableView.identifier, bundle: nil)
    register(
      nib,
      forSupplementaryViewOfKind: UICollectionView.elementKindSectionFooter,
      withReuseIdentifier: reusableView.identifier
    )
  }

  /// Setup reusable cell
  /// - Parameters:
  ///   - class: Cell to reuse
  ///   - indexPath: Current index path
  ///   - configure: Configure cell if needed
  /// - Returns: Configurable cell
  public func dequeueReusableCell<T: UICollectionViewCell>(of class: T.Type,
                                                           for indexPath: IndexPath,
                                                           configure: ((T) -> Void)? = nil) -> UICollectionViewCell {
    let cell = dequeueReusableCell(withReuseIdentifier: T.identifier, for: indexPath)
    if let typedCell = cell as? T {
      configure?(typedCell)
    }
    return cell
  }

  /// Setup reusable header cell
  /// - Parameters:
  ///   - class: Header view to reuse
  ///   - indexPath: Current index path
  ///   - configure: Configure header if needed
  /// - Returns: Configurable header view
  public func dequeueReusableHeader<T: UICollectionReusableView>(of class: T.Type,
                                                                 for indexPath: IndexPath,
                                                                 configure: ((T) -> Void)? = nil) -> UICollectionReusableView {
    let header = dequeueReusableSupplementaryView(
      ofKind: UICollectionView.elementKindSectionHeader,
      withReuseIdentifier: T.identifier,
      for: indexPath
    )
    if let headerCell = header as? T {
      configure?(headerCell)
    }
    return header
  }

  /// Setup reusable footer cell
  /// - Parameters:
  ///   - class: Footer view to reuse
  ///   - indexPath: Current index path
  ///   - configure: Configure footer if needed
  /// - Returns: Configurable footer view
  public func dequeueReusableFooter<T: UICollectionReusableView>(of class: T.Type,
                                                                 for indexPath: IndexPath,
                                                                 configure: ((T) -> Void)? = nil) -> UICollectionReusableView {
    let footer = dequeueReusableSupplementaryView(
      ofKind: UICollectionView.elementKindSectionFooter,
      withReuseIdentifier: T.identifier,
      for: indexPath
    )
    if let footerCell = footer as? T {
      configure?(footerCell)
    }
    return footer
  }
}

extension NSObject {
  public var identifier: String {
    String(describing: type(of: self))
  }

  public static var identifier: String {
    String(describing: self)
  }
}