---
title: index
framework: metal
role: symbol
role_heading: Instance Property
path: metal/mtlfunctionconstant/index
---

# index

The index of the function constant.

## Declaration

```swift
var index: Int { get }
```

## See Also

### Reading the function constant’s properties

- [name](metal/mtlfunctionconstant/name.md)
- [type](metal/mtlfunctionconstant/type.md)
- [required](metal/mtlfunctionconstant/required.md)