---
title: identifier
framework: arkit
role: symbol
role_heading: Instance Property
path: arkit/arsession/identifier
---

# identifier

A unique identifier of the running session.

## Declaration

```swift
var identifier: UUID { get }
```

## Discussion

Discussion This property might change after you call the run function, but not immediately. Therefore, to get the new value, listen for its change using key-value observation. // Use key-value observation to monitor my ARSession's identifier. var sessionIDObservation: NSKeyValueObservation? ... sessionIDObservation = observe(     .arView.session.identifier,     options: [.old, .new]) {          object, change in         print("SessionID changed to: \(change.newValue!)")     }

## See Also

### Configuring and running a session

- [run(_:options:)](arkit/arsession/run(_:options:).md)
- [ARSession.RunOptions](arkit/arsession/runoptions.md)
- [configuration](arkit/arsession/configuration.md)
- [pause()](arkit/arsession/pause().md)