AFProximity Status
Represents the proximity status of a beacon. This sealed class has three possible states:
Nearby: The beacon is considered to be in close proximity.beacon: TheAFBeaconobject representing the nearby beacon.distanceMeters: An optionalDoublerepresenting the estimated distance to the beacon in meters. This can benullif the distance cannot be determined.Far: The beacon is detected but is not considered to be in close proximity.beacon: TheAFBeaconobject representing the far beacon.Unknown: The proximity status of the beacon cannot be determined.beacon: TheAFBeaconobject for which the proximity is unknown.