---
title: partIndex
framework: hvf
role: symbol
role_heading: Instance Property
platforms: [iOS 18.4+, iPadOS 18.4+, Mac Catalyst 18.4+, macOS 15.4+, tvOS 18.4+, visionOS 2.4+, watchOS 11.4+]
path: hvf/partrenderer/partindex
---

# partIndex

The unique identifier of the part to be rendered. Setting this resets the parameters property to default values (an empty part parameter tree). Any previously captured PartParameters or AxisValues are invalid.

## Declaration

```swift
var partIndex: Int { get set }
```