---
title: opacityCurve
framework: realitykit
role: symbol
role_heading: Instance Property
path: realitykit/particleemittercomponent/particleemitter/opacitycurve-swift.property
---

# opacityCurve

The curve of opacity change over the lifetime of the particle. Defaults to quickFadeInOut.

## Declaration

```swift
var opacityCurve: ParticleEmitterComponent.ParticleEmitter.OpacityCurve
```