# LowLevelMesh.PartsCollection An object that holds a mutable collection low-level mesh parts. ``` struct PartsCollection ``` ## Topics ### Updating collection contents [`func append(LowLevelMesh.PartsCollection.Element)`](/documentation/RealityKit/LowLevelMesh/PartsCollection/append(_:)) Adds an element to the end of the collection. [`func append(contentsOf: S)`](/documentation/RealityKit/LowLevelMesh/PartsCollection/append(contentsOf:)) Adds the elements of a sequence or collection to the end of this collection. [`func replaceAll(S)`](/documentation/RealityKit/LowLevelMesh/PartsCollection/replaceAll(_:)) Replaces all mesh parts in this collection with those from the new sequence. [`func removeAll()`](/documentation/RealityKit/LowLevelMesh/PartsCollection/removeAll()) Removes all mesh parts from this collection. ## Relationships ### Conforms To [`Copyable`](/documentation/Swift/Copyable) [`MutableCollection`](/documentation/Swift/MutableCollection) [`Escapable`](/documentation/Swift/Escapable) [`RandomAccessCollection`](/documentation/Swift/RandomAccessCollection) [`Sequence`](/documentation/Swift/Sequence) [`BidirectionalCollection`](/documentation/Swift/BidirectionalCollection) [`Collection`](/documentation/Swift/Collection) --- 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)