---
title: willPopUpNotification
framework: appkit
role: symbol
role_heading: Type Property
path: appkit/nspopupbutton/willpopupnotification
---

# willPopUpNotification

Posted when an NSPopUpButton object receives a mouse-down event—that is, when the user is about to select an item from the menu.

## Declaration

```swift
class let willPopUpNotification: NSNotification.Name
```

## Discussion

Discussion The notification object is the selected NSPopUpButton object. This notification does not contain a userInfo dictionary. To observe this notification using Swift concurrency, use NSPopUpButton.WillPopUpMessage.