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# NSCollectionLayoutGroupCustomItemProvider

A closure that creates and returns each of the custom group’s items.

```
typealias NSCollectionLayoutGroupCustomItemProvider = (any NSCollectionLayoutEnvironment) -> [NSCollectionLayoutGroupCustomItem]
```

## Discussion

You use a custom item provider to supply the item arrangement when creating a group using the [`custom(layoutSize:itemProvider:)`](/documentation/AppKit/NSCollectionLayoutGroup/custom(layoutSize:itemProvider:)) initializer.

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