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# calendarDayChanged

An identifier for a message about a change in calendar day.

```
static var calendarDayChanged: NotificationCenter.BaseMessageIdentifier<Calendar.CalendarDayChangedMessage> { get }
```

## Discussion

Use this identifier with [`NotificationCenter`](/documentation/Foundation/NotificationCenter)’s `addObserver(of:for:using:)` or `messages(of:for:bufferSize:)` methods to observe messages of type [`Calendar.CalendarDayChangedMessage`](/documentation/Foundation/Calendar/CalendarDayChangedMessage).

---

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