---
title: "apply(_:animatingDifferences:completion:)"
framework: uikit
role: symbol
role_heading: Instance Method
path: "uikit/uicollectionviewdiffabledatasource-9tqpa/apply(_:animatingdifferences:completion:)"
---

# apply(_:animatingDifferences:completion:)

Updates the UI to reflect the state of the data in the snapshot, optionally animating the UI changes and executing a completion handler.

## Declaration

```swift
@MainActor @preconcurrency func apply(_ snapshot: NSDiffableDataSourceSnapshot<SectionIdentifierType, ItemIdentifierType>, animatingDifferences: Bool = true, completion: (() -> Void)? = nil)
```

## Parameters

- `snapshot`: The snapshot that reflects the new state of the data in the collection view.
- `animatingDifferences`: If doc://com.apple.documentation/documentation/Swift/true, the system animates the updates to the collection view. If doc://com.apple.documentation/documentation/Swift/false, the system doesn’t animate the updates to the collection view.
- `completion`: A closure to execute when the animations are complete. This closure has no return value and takes no parameters. The system calls this closure from the main queue.

## Discussion

Discussion The diffable data source computes the difference between the collection view’s current state and the new state in the applied snapshot, which is an O(n) operation, where n is the number of items in the snapshot. You can safely call this method from a background queue, but you must do so consistently in your app. Always call this method exclusively from the main queue or from a background queue.

## See Also

### Updating data

- [snapshot()](uikit/uicollectionviewdiffabledatasource-9tqpa/snapshot().md)
- [apply(_:animatingDifferences:)](uikit/uicollectionviewdiffabledatasource-9tqpa/apply(_:animatingdifferences:).md)
- [applySnapshotUsingReloadData(_:)](uikit/uicollectionviewdiffabledatasource-9tqpa/applysnapshotusingreloaddata(_:).md)
- [applySnapshotUsingReloadData(_:completion:)](uikit/uicollectionviewdiffabledatasource-9tqpa/applysnapshotusingreloaddata(_:completion:).md)