---
title: indexBuffer
framework: metal
role: symbol
role_heading: Instance Property
path: metal/mtlaccelerationstructurecurvegeometrydescriptor/indexbuffer
---

# indexBuffer

A buffer that contains references to control points in the control point buffer.

## Declaration

```swift
var indexBuffer: (any MTLBuffer)? { get set }
```

## Discussion

Discussion This property needs to have a non-nil value when you build an acceleration structure.