---
title: FSMutableFileDataBuffer
framework: fskit
role: symbol
role_heading: Class
path: fskit/fsmutablefiledatabuffer
---

# FSMutableFileDataBuffer

A wrapper object for a data buffer.

## Declaration

```swift
class FSMutableFileDataBuffer
```

## Overview

Overview This object provides a “zero-copy” buffer, for use when reading data from files. By not requiring additional buffer copying, this object reduces the extension’s memory footprint and improves performance. The FSMutableFileDataBuffer behaves similarly to a uio in the kernel.

## Topics

### Accessing buffer properties

- [withUnsafeMutableBytes(_:)](fskit/fsmutablefiledatabuffer/withunsafemutablebytes(_:).md)
- [length](fskit/fsmutablefiledatabuffer/length.md)

### Instance Methods

- [createMutableRawSpan()](fskit/fsmutablefiledatabuffer/createmutablerawspan().md)

## Relationships

### Inherits From

- [NSObject](objectivec/nsobject-swift.class.md)

### Conforms To

- [CVarArg](swift/cvararg.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [NSObjectProtocol](objectivec/nsobjectprotocol.md)

## See Also

### Reading and writing

- [read(from:at:length:into:replyHandler:)](fskit/fsvolume/readwritehandler/read(from:at:length:into:replyhandler:).md)
- [FSReadFileResult](fskit/fsreadfileresult.md)
- [write(contents:to:at:replyHandler:)](fskit/fsvolume/readwritehandler/write(contents:to:at:replyhandler:).md)
- [FSWriteFileResult](fskit/fswritefileresult.md)