---
title: "subscript(_:)"
framework: swiftui
role: symbol
role_heading: Instance Subscript
path: "swiftui/attributedtextformatting/attributecontainerproxy/subscript(_:)"
---

# subscript(_:)

Access the value of the attribute to constrain.

## Declaration

```swift
subscript(key: Attribute.Type) -> Attribute.Value? { get set }
```

## Overview

Overview For details on how attribute value constraining works, refer to constrain(_:).