Diffable data sources paged data

I was trying to implement a way of handling a paging mechanism with diffable data sources. I know the total number of items that can be displayed but only want to request 10 items at a time from the server, so the scroll bar can show to the maximum size of the data but when you scroll, grabs the paged in items on demand. I tried inserting dummy items, aka promises, but then they did not have a unique identifier and it produced an exception. Then I tried added, dummy items with an associated index, but this seemed hacky. Is there an elegant way of handling paged in results, when you know the maximum number of items?