---
title: FSExtentPacker
framework: fskit
role: symbol
role_heading: Class
path: fskit/fsextentpacker
---

# FSExtentPacker

A type that directs the kernel to map space on disk to a specific file managed by this file system.

## Declaration

```swift
class FSExtentPacker
```

## Overview

Overview Extents provide the kernel the logical-to-physical mapping of a given file. An extent describes a physical offset on disk, and a length and a logical offset within the file. Rather than working with extents directly, you use this type’s methods to provide or “pack” extent information, which FSKit then passes to the kernel.

## Topics

### Packing extents

- [packExtent(resource:type:logicalOffset:physicalOffset:length:)](fskit/fsextentpacker/packextent(resource:type:logicaloffset:physicaloffset:length:).md)
- [FSExtentType](fskit/fsextenttype.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

### Supporting types

- [FSBlockmapFlags](fskit/fsblockmapflags.md)
- [FSCompleteIOFlags](fskit/fscompleteioflags.md)
- [FSEntityIdentifier](fskit/fsentityidentifier.md)
- [FSExtentType](fskit/fsextenttype.md)
- [FSMatchResult](fskit/fsmatchresult.md)
- [FSMetadataRange](fskit/fsmetadatarange.md)
- [FSProbeResult](fskit/fsproberesult.md)