---
title: SCNParticleEvent.collision
framework: scenekit
role: symbol
role_heading: Case
path: scenekit/scnparticleevent/collision
---

# SCNParticleEvent.collision

Occurs when particles collide with scene geometry.

## Declaration

```swift
case collision
```

## Discussion

Discussion SceneKit calls your event handler block immediately after resolving the collision.

## See Also

### Constants

- [SCNParticleEvent.birth](scenekit/scnparticleevent/birth.md)
- [SCNParticleEvent.death](scenekit/scnparticleevent/death.md)