Signaling Changes for User-Driven Actions

Overview

You must let the system know about any changes so that it can update the document browser’s interface as needed. For some actions, the browser displays transient items while the action is in progress. The signal tells the browser that the action has completed, letting the system clean up the browser’s interface. The signal also provides updated information for any items that are currently on display.

You may need to signal the item itself, the item’s parent (both the new parent and the old parent for move actions), and the working set.

For any action, follow these steps:

1. Check the item’s parent. If you have an active enumerator for the parent, signal the parent.

2. Check the item itself. If you have an active enumerator for the item, signal the item.

3. If the item is in the working set, signal the working set.

4. If the action adds items to the working set (or removes them), signal the working set.

5. If the item’s parent is in the working set, and the action adds or removes items from the parent, signal the working set.

Signal the change by calling the NSFileProviderManager class’s signalEnumerator(for:completionHandler:) method and passing in the proper identifier. For the working set, use the workingSet identifier.

After the system is alerted to the change, it calls enumerateChanges(for:from:) on any active enumerations that are affected and updates the browser’s user interface as needed.

For more information, see Tracking Your File Provider’s Changes.