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

# subscript(_:)

Accesses the environment value associated with a custom key.

## Declaration

```swift
subscript<K>(key: K.Type) -> K.Value where K : EnvironmentKey { get set }
```

## Overview

Overview Create a custom environment value by declaring a new property in an extension to the environment values structure and applying the Entry() macro to the variable declaration: extension EnvironmentValues {     @Entry var myCustomValue: String = "Default value" } You use custom environment values the same way you use system-provided values, setting a value with the environment(_:_:) view modifier, and reading values with the Environment property wrapper. You can also provide a dedicated view modifier as a convenience for setting the value: extension View {     func myCustomValue(_ myCustomValue: String) -> some View {         environment(\.myCustomValue, myCustomValue)     } }

## See Also

### Creating and accessing values

- [init()](swiftui/environmentvalues/init().md)
- [description](swiftui/environmentvalues/description.md)