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

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

```
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

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.

---

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