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# NSCollectionViewUpdateItem

A description of a single change to make to an item in a collection view.

```
@MainActor class NSCollectionViewUpdateItem
```

## Overview

You do not create instances of this class directly. When updating its content, the collection view object creates them and passes them to the layout object’s [`prepare(forCollectionViewUpdates:)`](/documentation/AppKit/NSCollectionViewLayout/prepare(forCollectionViewUpdates:)) method, which can use them to prepare for the upcoming changes.

## Topics

### Accessing the Item Changes

[`indexPathBeforeUpdate`](/documentation/AppKit/NSCollectionViewUpdateItem/indexPathBeforeUpdate)

The index path of the item before the update.

[`indexPathAfterUpdate`](/documentation/AppKit/NSCollectionViewUpdateItem/indexPathAfterUpdate)

The index path of the item after the update.

[`updateAction`](/documentation/AppKit/NSCollectionViewUpdateItem/updateAction)

The action being performed on the item.

[`NSCollectionView.UpdateAction`](/documentation/AppKit/NSCollectionView/UpdateAction)

Constants indicating the type of action being performed on an item.

[`NSCollectionView.ScrollDirection`](/documentation/AppKit/NSCollectionView/ScrollDirection)

Constants indicating the scrolling direction for the layout.

### Constants

[`NSCollectionView.UpdateAction`](/documentation/AppKit/NSCollectionView/UpdateAction)

Constants indicating the type of action being performed on an item.


---

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