---
title: "replaceIndices(_:)"
framework: realitykit
role: symbol
role_heading: Instance Method
path: "realitykit/lowlevelmeshresource/replaceindices(_:)"
---

# replaceIndices(_:)

Replaces the index buffer synchronously on the CPU. The buffer’s contents are unspecified; you must populate the buffer with valid data.

## Declaration

```swift
final func replaceIndices<R, E>(_ body: @_lifetime(0: copy 0) (inout MutableRawSpan) throws(E) -> R) throws(E) -> R where E : Error, R : ~Copyable
```

## Parameters

- `body`: A closure that receives a mutable span over the index buffer’s bytes to fully populate.

## Discussion

Discussion note: Any error thrown by body.

## See Also

### Accessing index data

- [readIndices(_:)](realitykit/lowlevelmeshresource/readindices(_:).md)
- [updateIndices(_:)](realitykit/lowlevelmeshresource/updateindices(_:).md)
- [readIndices(commandBuffer:)](realitykit/lowlevelmeshresource/readindices(commandbuffer:).md)
- [replaceIndices(commandBuffer:)](realitykit/lowlevelmeshresource/replaceindices(commandbuffer:).md)