---
title: didChange
framework: foundation
role: symbol
role_heading: Type Property
path: foundation/notificationcenter/messageidentifier/didchange-187tw
---

# didChange

An identifier for a message about a change in a user defaults setting.

## Declaration

```swift
static var didChange: NotificationCenter.BaseMessageIdentifier<UserDefaults.DidChangeMessage> { get }
```

## Discussion

Discussion Use this identifier with NotificationCenter’s addObserver(of:for:using:) or messages(of:for:bufferSize:) methods to observe messages of type UserDefaults.DidChangeMessage.

## See Also

### Identifying defaults messages

- [sizeLimitExceeded](foundation/notificationcenter/messageidentifier/sizelimitexceeded.md)