how to limit the user's previewing page?

In our purpose, we want to prompt a download alert when users previewed some pages of the file .
For instance , when previewing page 5 , we alert "Will you download the whole file? "
In that case , we have to monitor the current page while previewing .
Is there a method or delegate to achieve that? I found a class called BOXPreviewerPageTrackerManager-> userSwipedDocumentToPage:(NSNumber *)page forFile:(BOXFile *)file seems to work on this , But how can I implement this ?
Thanks .

Start with BOXPreviewerPageTrackerManager and its userSwipedDocumentToPage:forFile: method, which the issue identifies as relevant to tracking preview pages. Check the SDK's available callbacks or delegate usage and determine whether page 5 can trigger the requested alert. Done means documenting a supported implementation path or confirming the limitation.

Written by the indexing model from the issue text.