---
title: systemSpawnedOnCollision
framework: scenekit
role: symbol
role_heading: Instance Property
path: scenekit/scnparticlesystem/systemspawnedoncollision
---

# systemSpawnedOnCollision

Another particle system to be added to the scene when a particle collides with scene geometry.

## Declaration

```swift
var systemSpawnedOnCollision: SCNParticleSystem? { get set }
```

## Discussion

Discussion When a particle collides with scene geometry, SceneKit adds a copy of the specified particle system to the scene at the location of the collision. (To define collision behavior, see the colliderNodes property.) Use this property to simulate effects such as rain—one particle system simulates falling raindrops, and another particle system simulates the splashes that occur where each raindrop strikes a surface. The default value of this property is nil, specifying that no additional systems are added to the scene on particle collision. important: Adding a new particle system to the scene for each collision can drastically increase the total number of rendered particles. To maintain adequate rendering performance, set the loops property to false for any particle system you assign to the systemSpawnedOnCollision property.

## See Also

### Spawning Additional Particle Systems

- [systemSpawnedOnDying](scenekit/scnparticlesystem/systemspawnedondying.md)
- [systemSpawnedOnLiving](scenekit/scnparticlesystem/systemspawnedonliving.md)