A growing number of checkin/checkout systems are using iBeacons. Having an iBeacon at an entrance to a building allows employees to be automatically clocked in and out. It provides confirmation that a worker did actually arrive at a certain place that day.
PeopleHR is one such solution that has information and a blog post on how to set up tap in and out using beacons.
Checkin/out systems use the iBeacon type of beacon because it can be detected on iOS (and Android) even when the app isn’t in foreground.