---
title: "withMutableTransforms(_:)"
framework: realitykit
role: symbol
role_heading: Instance Method
path: "realitykit/lowlevelinstancedata/withmutabletransforms(_:)"
---

# withMutableTransforms(_:)

Updates the per instance transform data synchronously on the CPU.

## Declaration

```swift
final func withMutableTransforms(_ callback: (UnsafeMutableBufferPointer<float4x4>) -> Void)
```

## Discussion

Discussion The transform buffer provided is only valid for the lifetime of the callback.