---
title: "browser(_:previewViewControllerForLeafItem:)"
framework: appkit
role: symbol
role_heading: Instance Method
path: "appkit/nsbrowserdelegate/browser(_:previewviewcontrollerforleafitem:)"
---

# browser(_:previewViewControllerForLeafItem:)

Asks the delegate for a controller that provides a preview column for the specified leaf item.

## Declaration

```swift
@MainActor optional func browser(_ browser: NSBrowser, previewViewControllerForLeafItem item: Any) -> NSViewController?
```

## Parameters

- `browser`: The browser.
- `item`: The leaf item.

## Return Value

Return Value A view controller that provides a preview column, or nil to suppress the preview column.

## Discussion

Discussion The returned controller’s represented object is set to the specified leaf item. This method is called only if the delegate implements the item data source methods.

## See Also

### Accessing Components

- [browser(_:child:ofItem:)](appkit/nsbrowserdelegate/browser(_:child:ofitem:).md)
- [browser(_:isLeafItem:)](appkit/nsbrowserdelegate/browser(_:isleafitem:).md)
- [browser(_:shouldEditItem:)](appkit/nsbrowserdelegate/browser(_:shouldedititem:).md)
- [browser(_:objectValueForItem:)](appkit/nsbrowserdelegate/browser(_:objectvalueforitem:).md)
- [browser(_:setObjectValue:forItem:)](appkit/nsbrowserdelegate/browser(_:setobjectvalue:foritem:).md)
- [rootItem(for:)](appkit/nsbrowserdelegate/rootitem(for:).md)
- [browser(_:headerViewControllerForItem:)](appkit/nsbrowserdelegate/browser(_:headerviewcontrollerforitem:).md)