---
title: "collectionView(_:willDisplaySupplementaryView:forElementKind:at:)"
framework: uikit
role: symbol
role_heading: Instance Method
path: "uikit/uicollectionviewdelegate/collectionview(_:willdisplaysupplementaryview:forelementkind:at:)"
---

# collectionView(_:willDisplaySupplementaryView:forElementKind:at:)

Tells the delegate that the specified supplementary view is about to be displayed in the collection view.

## Declaration

```swift
optional func collectionView(_ collectionView: UICollectionView, willDisplaySupplementaryView view: UICollectionReusableView, forElementKind elementKind: String, at indexPath: IndexPath)
```

## Parameters

- `collectionView`: The collection view object that is adding the supplementary view.
- `view`: The view being added.
- `elementKind`: The type of the supplementary view. This string is defined by the layout that presents the view.
- `indexPath`: The index path of the data item that the supplementary view represents.

## Discussion

Discussion The collection view calls this method before adding a supplementary view to its content. Use this method to detect view additions, as opposed to monitoring the view itself to see when it appears.

## See Also

### Tracking the addition and removal of views

- [collectionView(_:willDisplay:forItemAt:)](uikit/uicollectionviewdelegate/collectionview(_:willdisplay:foritemat:).md)
- [collectionView(_:didEndDisplaying:forItemAt:)](uikit/uicollectionviewdelegate/collectionview(_:didenddisplaying:foritemat:).md)
- [collectionView(_:didEndDisplayingSupplementaryView:forElementOfKind:at:)](uikit/uicollectionviewdelegate/collectionview(_:didenddisplayingsupplementaryview:forelementofkind:at:).md)