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# idleDuration

The duration, in seconds, of periods when the system emits no particles. Animatable.

```
var idleDuration: CGFloat { get set }
```

## Discussion

If the system’s [`loops`](/documentation/SceneKit/SCNParticleSystem/loops) property value is <doc://com.apple.documentation/documentation/Swift/true>, you can make the system emit particles periodically or sporadically. For example, in a looping system where the [`emissionDuration`](/documentation/SceneKit/SCNParticleSystem/emissionDuration) value is `1.0` seconds and the [`idleDuration`](/documentation/SceneKit/SCNParticleSystem/idleDuration) value is `1.0` seconds, the system alternates between equal one-second periods of spawning and not spawning particles. You can randomize the duration with the [`idleDurationVariation`](/documentation/SceneKit/SCNParticleSystem/idleDurationVariation) property. Idle duration has no effect if the [`loops`](/documentation/SceneKit/SCNParticleSystem/loops) property value is <doc://com.apple.documentation/documentation/Swift/false>.

The default value is `0.0` seconds, specifying no idle time between emissions. (That is, if the [`loops`](/documentation/SceneKit/SCNParticleSystem/loops) property value is <doc://com.apple.documentation/documentation/Swift/true>, the system emits particles continuously.)

You can animate changes to this property’s value. See [Animating SceneKit Content](/documentation/SceneKit/animating-scenekit-content).

---

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