---
title: SFExtensionMessageKey
framework: safariservices
role: symbol
role_heading: Global Variable
path: safariservices/sfextensionmessagekey
---

# SFExtensionMessageKey

A string the system uses as a key in a user info dictionary to identify a message.

## Declaration

```swift
let SFExtensionMessageKey: String
```

## Mentioned in

Messaging between the app and JavaScript in a Safari web extension

## See Also

### Messaging

- [Messaging between the app and JavaScript in a Safari web extension](safariservices/messaging-between-the-app-and-javascript-in-a-safari-web-extension.md)
- [SFExtensionProfileKey](safariservices/sfextensionprofilekey.md)
- [Messaging a Web Extension’s Native App](safariservices/messaging-a-web-extension-s-native-app.md)
- [Messaging between a webpage and your Safari web extension](safariservices/messaging-between-a-webpage-and-your-safari-web-extension.md)