Now that you can cache both RSS feeds, let’s add another useful feature: when the user selects an RSSItem, we want the ListViewController to add an indicator to the table that shows that this item has been read (Figure 29.7). Even if the user closes the application, the list of read items should persist. Nerdfeed, then, needs to store the list of read RSSItems on the filesystem.

The simplest way to add this feature would be to add a hasBeenRead Boolean instance variable to RSSItem. When the user tapped on a row, the corresponding RSSItem would change its value of hasBeenRead to YES. For each row in the table, a checkmark would be displayed if the corresponding RSSItem’s hasBeenRead variable is YES.