---
title: propertyControllers
framework: scenekit
role: symbol
role_heading: Instance Property
path: scenekit/scnparticlesystem/propertycontrollers
---

# propertyControllers

A dictionary that optionally associates particle properties with objects that animate a property’s value for each particle.

## Declaration

```swift
var propertyControllers: [SCNParticleSystem.ParticleProperty : SCNParticlePropertyController]? { get set }
```

## Discussion

Discussion Each key in this dictionary is one of the constants listed in Particle Property Keys, and the value for each key is a SCNParticlePropertyController object responsible for varying that property over time. Use particle property controllers to add efficient animations that change the appearance or behavior of each particle emitted by the system. To add more complex behavior that cannot be described by a SCNParticlePropertyController object, use the addModifier(forProperties:at:modifier:) to add a particle modifier block. However, be aware that particle modifier blocks can severely impact rendering performance.

## See Also

### Modifying Particles Over Time

- [addModifier(forProperties:at:modifier:)](scenekit/scnparticlesystem/addmodifier(forproperties:at:modifier:).md)
- [removeModifiers(at:)](scenekit/scnparticlesystem/removemodifiers(at:).md)
- [removeAllModifiers()](scenekit/scnparticlesystem/removeallmodifiers().md)
- [SCNParticleSystem.ParticleProperty](scenekit/scnparticlesystem/particleproperty.md)
- [SCNParticleModifierStage](scenekit/scnparticlemodifierstage.md)
- [SCNParticleModifierBlock](scenekit/scnparticlemodifierblock.md)