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# windowNibName

The name of the document’s sole nib file.

```
var windowNibName: NSNib.Name? { get }
```

## Discussion

Using this name, `NSDocument` creates and instantiates a default instance of `NSWindowController` to manage the window. If your document has multiple nib files, each with its own single window, or if the default `NSWindowController` instance is not adequate for your purposes, you should override [`makeWindowControllers()`](/documentation/AppKit/NSDocument/makeWindowControllers()).

The default value of this property is `nil`. Subclasses must override it to specify a nib file name.

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