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# UnaryFileSystemExtension

A protocol for implementing a minimal file system as an app extension.

```
protocol UnaryFileSystemExtension : AppExtension
```

## Overview

Your app needs to do the following to implement a FSKit-compatible minimal file system:

1. Create a subclass of [`FSUnaryFileSystem`](/documentation/FSKit/FSUnaryFileSystem), which also conforms to [`FSUnaryFileSystemOperations`](/documentation/FSKit/FSUnaryFileSystemOperations).
2. Implement a `@main` struct that conforms to the `UnaryFileSystemExtension` protocol. Your implementation of this protocol returns the type of class from step 1 as its [`FileSystem`](/documentation/FSKit/UnaryFileSystemExtension/FileSystem-swift.associatedtype) associated type, and returns an instance of it as the [`fileSystem`](/documentation/FSKit/UnaryFileSystemExtension/fileSystem-swift.property) property.

## Topics

### Declaring the implemented file system

[`var fileSystem: Self.FileSystem`](/documentation/FSKit/UnaryFileSystemExtension/fileSystem-swift.property)

The instance of your file system type that your app extension provides.

[`associatedtype FileSystem : FSUnaryFileSystem, FSUnaryFileSystemOperations`](/documentation/FSKit/UnaryFileSystemExtension/FileSystem-swift.associatedtype)

The type of file system your app extension provides.

## Relationships

### Inherits From

[`AppExtension`](/documentation/ExtensionFoundation/AppExtension)

---

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