---
title: Subject
framework: foundation
role: symbol
role_heading: Associated Type
path: foundation/notificationcenter/mainactormessage/subject
---

# Subject

A type which you can optionally post and observe along with this MainActorMessage.

## Declaration

```swift
associatedtype Subject
```

## See Also

### Declaring the message name and subject

- [name](foundation/notificationcenter/mainactormessage/name.md)