---
title: supplementaryViewProvider
framework: appkit
role: symbol
role_heading: Instance Property
path: appkit/nscollectionviewdiffabledatasource-axww/supplementaryviewprovider-swift.property
---

# supplementaryViewProvider

The closure that configures and returns the collection view’s supplementary views, such as headers and footers, from the diffable data source.

## Declaration

```swift
var supplementaryViewProvider: NSCollectionViewDiffableDataSource<SectionIdentifierType, ItemIdentifierType>.SupplementaryViewProvider? { get set }
```

## See Also

### Creating Supplementary Views

- [NSCollectionViewDiffableDataSource.SupplementaryViewProvider](appkit/nscollectionviewdiffabledatasource-axww/supplementaryviewprovider-swift.typealias.md)