# AddExtension(IResourceCollectionExtension)

> Attaches an extension to this collection.

## Definition

* **Type:** Method
* **Namespace:** [Unity.Localization.Editor](/engine/6000.7/script-reference/unity/localization/editor.md)
* **Assembly:** UnityEditor

```csharp
public void AddExtension(IResourceCollectionExtension extension)
```

### Parameters

**** (\[IResourceCollectionExtension]\(/engine/6000.7/script-reference/unity/localization/editor/iresourcecollectionextension)): The extension to attach. Ignored when null or already attached.