You can create views with filters to show V4S attendees of a specific event
To create the view in Salesforce, go to the V4S Attendees tab and click the dropdown in the "List view controls" tab and click new. Select the fields as "Attendee Code, Contact, Volunteer Shift, QR Code, Status, Checked-In at, Checked-Out at, etc.," and save the list view. Now go to the list view filters, and select the Volunteer Shift field equals the Shift ID and save it.
Now the list view shows only the V4S Attendees of the Shift which was selected in the list view filters.
The view can be used to scan the Attendees and Check them In and Out of the Event.