# UniqueBox A smart pointer type that uniquely owns an instance of `Value` on the heap. ``` @frozen struct UniqueBox where Value : ~Copyable ``` ## Topics ### Initializers [`init(consuming Value)`](/documentation/Swift/UniqueBox/init(_:)) Initializes a value of this unqiue box with the given initial value. ### Instance Properties [`var mutableSpan: MutableSpan`](/documentation/Swift/UniqueBox/mutableSpan) A mutable span over the single element stored in this box. [`var span: Span`](/documentation/Swift/UniqueBox/span) A span over the single element stored in this box. [`var value: Value`](/documentation/Swift/UniqueBox/value) Dereferences the unique box allowing for in-place reads and writes to the stored `Value`. ### Instance Methods [`func clone() -> UniqueBox`](/documentation/Swift/UniqueBox/clone()) Copies the value within the unqiue box and returns it in a new unique instance. [`func consume() -> Value`](/documentation/Swift/UniqueBox/consume()) Consumes the unique box and returns the instance of `Value` that was within the box. ## Relationships ### Conforms To [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`Sendable`](/documentation/Swift/Sendable) --- 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)