# ItemCollection A tree structure containing annotations, overlays, and nested item collection objects. ``` class ItemCollection ``` ## Overview The [`importGeoJSON(data, callback)`](/documentation/MapKitJS/mapkit/importGeoJSON) method returns item collections. Don’t instantiate them directly. ## Topics ### Item collection properties [`get data(): D | null; set data(data: D | null);`](/documentation/MapKitJS/ItemCollection/data) The raw GeoJSON data. [`getFlattenedItemList(): (Annotation | Overlay)[];`](/documentation/MapKitJS/ItemCollection/getFlattenedItemList) A flattened array of items that includes annotations and overlays. [`get items(): Item[]; set items(items: Item | Item[] | null);`](/documentation/MapKitJS/ItemCollection/items) A nested list of annotations, overlays, and other item collections. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)