---
title: "withUnsafeMutablePointer(_:)"
framework: coreaudio
role: symbol
role_heading: Instance Method
path: "coreaudio/managedaudiochannellayout/withunsafemutablepointer(_:)"
---

# withUnsafeMutablePointer(_:)

Calls a closure with a mutable pointer to the backing AudioChannelLayout.

## Declaration

```swift
mutating func withUnsafeMutablePointer<Result>(_ body: (UnsafeMutablePointer<AudioChannelLayout>) throws -> Result) rethrows -> Result
```

## Parameters

- `body`: A closure that is called with a mutable pointer to the backing AudioChannelLayout.

## Discussion

Discussion It is invalid to increase mNumberChannelDescriptions.