---
title: Content and Change Tracking
framework: fileprovider
role: collectionGroup
role_heading: API Collection
path: fileprovider/content-and-change-tracking
---

# Content and Change Tracking

Create enumerators to specify your file provider’s content, and track changes to that content.

## Overview

Overview To display your file provider’s items to the user, you tell the system about those items and any changes to their contents. You do this by providing enumerators. To provide an enumerator, create a class that adopts the NSFileProviderEnumerator protocol. The system uses this enumerator to represent an item (a folder or a document) managed by your file provider. In addition, the system uses the enumerator to track any changes to the item. The system also uses an enumerator to track the working set (a set of special items like Recents or Favorites). You create enumerators to handle these use cases:  |  |   |  |   |  |   |  |   |  |  Once requested, an enumerator provides both the content and any changes for an item. When the system stops accessing the item, it calls the enumerator’s invalidate() method. For example, if you return an enumerator that provides the content of a directory, as long as the enumerator is active, the system also uses it to enumerate changes to the directory. The system may have multiple, active enumerators for different items. Some of these may represent items that are currently displayed on screen. Others may be items that are no longer displayed, but the system has retained the enumerator for performance reasons. You need to inform the system of any changes to the content managed by any of the active enumerators, as well as any changes to the working set (whether or not it has an active enumerator).

## Topics

### Essentials

- [NSFileProviderEnumerator](fileprovider/nsfileproviderenumerator.md)

### Content

- [Defining Your File Provider’s Content](fileprovider/defining-your-file-provider-s-content.md)
- [NSFileProviderEnumerationObserver](fileprovider/nsfileproviderenumerationobserver.md)
- [NSFileProviderPage](fileprovider/nsfileproviderpage.md)

### Change Tracking

- [Tracking Your File Provider’s Changes](fileprovider/tracking-your-file-provider-s-changes.md)
- [NSFileProviderChangeObserver](fileprovider/nsfileproviderchangeobserver.md)
- [NSFileProviderSyncAnchor](fileprovider/nsfileprovidersyncanchor.md)

## See Also

### Nonreplicated extension

- [NSFileProviderExtension](fileprovider/nsfileproviderextension.md)