<!--
{
  "availability" : [
    "iOS: 27.0.0 -",
    "iPadOS: 27.0.0 -",
    "visionOS: 27.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "RealityKit",
  "identifier" : "/documentation/RealityKit/ClothSimulationEvents/BeforeUpdate",
  "metadataVersion" : "0.1.0",
  "role" : "Structure",
  "symbol" : {
    "kind" : "Structure",
    "modules" : [
      "RealityKit"
    ],
    "preciseIdentifier" : "s:22RealityFoundationCloth0C16SimulationEventsO12BeforeUpdateV"
  },
  "title" : "ClothSimulationEvents.BeforeUpdate"
}
-->

# ClothSimulationEvents.BeforeUpdate

An event type that a cloth simulation publishes immediately before performing an update.

```
struct BeforeUpdate
```

## Topics

### Inspecting the update

[`let simulationEntity: Entity`](/documentation/RealityKit/ClothSimulationEvents/BeforeUpdate/simulationEntity)

The entity that has the simulation component that this event originates from.

[`let updateCount: UInt64`](/documentation/RealityKit/ClothSimulationEvents/BeforeUpdate/updateCount)

The total number of updates in the simulation including the next update that immediately follows this event.

### Instance Properties

[`let deltaTime: TimeInterval`](/documentation/RealityKit/ClothSimulationEvents/BeforeUpdate/deltaTime)

The duration of the simulation update, in seconds, that this event represents.

## Relationships

### Conforms To

[`SendableMetatype`](/documentation/Swift/SendableMetatype)

[`Sendable`](/documentation/Swift/Sendable)

[`Event`](/documentation/RealityKit/Event)

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)