title: DiffableDataSource with multiple cell types
body: <p>I'm looking at DiffableDataSource available in iOS13 (or backported here: <a href="https://github.com/ra1028/DiffableDataSources" rel="noreferrer">https://github.com/ra1028/DiffableDataSources</a>) and cannot figure out how one would support multiple cell types in your collection or tableview.</p>
  
  <p>Apple's sample code<a href="https://developer.apple.com/documentation/uikit/views_and_controls/collection_views/using_collection_view_compositional_layouts_and_diffable_data_sources" rel="noreferrer">1</a> has:</p>
  
  <pre><code>var dataSource: UICollectionViewDiffableDataSource&lt;Section, OutlineItem&gt;! = nil
  </code></pre>
  
  <p>which seems to force a data source to be a single cell type. If I create a separate data source for another cell type - then there is no guarantee that both data sources don't have <code>apply</code> called on them at the same time - which would lead to the dreaded <code>NSInternalInconsistencyException</code> - which is familiar to anyone who has attempted to animate cell insertion/deletion manually with <code>performBatchUpdates</code>.</p>
  
  <p>Am I missing something obvious?</p>