Although it isn't currently documented (I'm submitting a documentation update, but who knows when/if it will be posted), the UITableViewDelegate methods:
- tableView:shouldShowMenuForRowAtIndexPath:
- tableView:canPerformAction:forRowAtIndexPath:withSender:
- tableView:performAction:forRowAtIndexPath:withSender:
are only called if your table view instance is managed by an instance of UITableViewController. A standalone table view will not have these methods invoked.
If your table view isn't connected to a table view controller, then you'll need to display the UIMenuController manually from long tap listeners (to duplicate the standard system functionality) on each table view cell.