---
title: "outlineViewItemWillCollapse(_:)"
framework: appkit
role: symbol
role_heading: Instance Method
path: "appkit/nsoutlineviewdelegate/outlineviewitemwillcollapse(_:)"
---

# outlineViewItemWillCollapse(_:)

Invoked when notification is posted—that is, whenever the user is about to collapse an item in the outline view.

## Declaration

```swift
@MainActor optional func outlineViewItemWillCollapse(_ notification: Notification)
```

## Parameters

- `notification`: The posted notification.

## Discussion

Discussion This method is invoked as a result of posting an itemWillCollapseNotification.

## See Also

### Working with the Outline Column

- [outlineViewColumnDidMove(_:)](appkit/nsoutlineviewdelegate/outlineviewcolumndidmove(_:).md)
- [outlineViewColumnDidResize(_:)](appkit/nsoutlineviewdelegate/outlineviewcolumndidresize(_:).md)
- [outlineViewItemWillExpand(_:)](appkit/nsoutlineviewdelegate/outlineviewitemwillexpand(_:).md)
- [outlineViewItemDidExpand(_:)](appkit/nsoutlineviewdelegate/outlineviewitemdidexpand(_:).md)
- [outlineViewItemDidCollapse(_:)](appkit/nsoutlineviewdelegate/outlineviewitemdidcollapse(_:).md)