---
title: mutableSpan
framework: Swift
role: symbol
role_heading: Instance Property
platforms: [iOS 27.0+, iPadOS 27.0+, Mac Catalyst 27.0+, macOS 27.0+, tvOS 27.0+, visionOS 27.0+, watchOS 27.0+]
path: swift/uniquebox/mutablespan
---

# mutableSpan

A mutable span over the single element stored in this box.

## Declaration

```swift
var mutableSpan: MutableSpan<Value> { mutating get }
```

## Return Value

Return Value A MutableSpan over the element stored in this box.

## Discussion

Discussion note: O(1)