---
title: didBecomeMainNotification
framework: appkit
role: symbol
role_heading: Type Property
path: appkit/nswindow/didbecomemainnotification
---

# didBecomeMainNotification

A notification that the window object became the main window.

## Declaration

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

## Discussion

Discussion The notification object is the NSWindow object that has become the main window. This notification doesn’t contain a userInfo dictionary. To observe this notification using Swift concurrency, use NSWindow.DidBecomeMainMessage.

## See Also

### Notifications

- [didBecomeKeyNotification](appkit/nswindow/didbecomekeynotification.md)
- [didChangeScreenNotification](appkit/nswindow/didchangescreennotification.md)
- [didChangeScreenProfileNotification](appkit/nswindow/didchangescreenprofilenotification.md)
- [didDeminiaturizeNotification](appkit/nswindow/diddeminiaturizenotification.md)
- [didEndSheetNotification](appkit/nswindow/didendsheetnotification.md)
- [didEndLiveResizeNotification](appkit/nswindow/didendliveresizenotification.md)
- [didExposeNotification](appkit/nswindow/didexposenotification.md)
- [didMiniaturizeNotification](appkit/nswindow/didminiaturizenotification.md)
- [didMoveNotification](appkit/nswindow/didmovenotification.md)
- [didResignKeyNotification](appkit/nswindow/didresignkeynotification.md)
- [didResignMainNotification](appkit/nswindow/didresignmainnotification.md)
- [didResizeNotification](appkit/nswindow/didresizenotification.md)
- [didUpdateNotification](appkit/nswindow/didupdatenotification.md)
- [willBeginSheetNotification](appkit/nswindow/willbeginsheetnotification.md)
- [willCloseNotification](appkit/nswindow/willclosenotification.md)