UICollectionView reusable

UICollectionView+Reusable.swift

extension UICollectionView {

  func registerCell<T: ReusableCell>(cellType: T.Type) {
    if let identifier = T.reuseIdentifier() {
      self.registerNib(T.uiNibFromClass(), forCellWithReuseIdentifier: identifier)
    }
  }

  func dequeueReusableCell<T: UICollectionViewCell>(index: Int) -> T {
    return dequeueReusableCell(NSIndexPath(forItem: index, inSection: 0))
  }

  func dequeueReusableCell<T: UICollectionViewCell>(indexPath: NSIndexPath) -> T {
    return dequeueReusableCellWithReuseIdentifier(T.className, forIndexPath: indexPath) as? T ?? T()
  }
}