Use UIViewController as UICollectionViewCell

gistfile1.swift

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: EmtyCell.name, for: indexPath)
    
    var viewController = YourViewController()
    
    cell.contentView.addSubview(viewController.view)

    viewController.view.translatesAutoresizingMaskIntoConstraints = false
        
    cell.contentView.addConstraint(NSLayoutConstraint(item: viewController.view!, attribute: .leading, relatedBy: .equal, toItem: cell.contentView, attribute: .leading, multiplier: 1.0, constant: 0.0))
        
    cell.contentView.addConstraint(NSLayoutConstraint(item: viewController.view!, attribute: .trailing, relatedBy: .equal, toItem: cell.contentView, attribute: .trailing, multiplier: 1.0, constant: 0.0))
    
    cell.contentView.addConstraint(NSLayoutConstraint(item: viewController.view!, attribute: .top, relatedBy: .equal, toItem: cell.contentView, attribute: .top, multiplier: 1.0, constant: 0.0))

    cell.contentView.addConstraint(NSLayoutConstraint(item: viewController.view!, attribute: .bottom, relatedBy: .equal, toItem: cell.contentView, attribute: .bottom, multiplier: 1.0, constant: 0.0))

    viewController.didMove(toParent: self)
    viewController.view.layoutIfNeeded()
    
    return cell
  }