---
title: eventNumber
framework: appkit
role: symbol
role_heading: Instance Property
path: appkit/nsevent/eventnumber
---

# eventNumber

The counter value of the latest mouse or tracking-rectangle event object.

## Declaration

```swift
var eventNumber: Int { get }
```

## Discussion

Discussion Every system-generated mouse and tracking-rectangle event increments this counter. If you access this property on an event of an unsupported type, AppKit raises internalInconsistencyException.

## See Also

### Related Documentation

- [enterExitEvent(with:location:modifierFlags:timestamp:windowNumber:context:eventNumber:trackingNumber:userData:)](appkit/nsevent/enterexitevent(with:location:modifierflags:timestamp:windownumber:context:eventnumber:trackingnumber:userdata:).md)
- [mouseEvent(with:location:modifierFlags:timestamp:windowNumber:context:eventNumber:clickCount:pressure:)](appkit/nsevent/mouseevent(with:location:modifierflags:timestamp:windownumber:context:eventnumber:clickcount:pressure:).md)

### Getting tracking area information

- [trackingNumber](appkit/nsevent/trackingnumber.md)
- [trackingArea](appkit/nsevent/trackingarea.md)
- [userData](appkit/nsevent/userdata.md)