---
title: childForPreferredVerticalBarBehavior
framework: UIKit
role: symbol
role_heading: Instance Property
platforms: [iOS 27.1+, iPadOS 27.1+]
path: uikit/uiviewcontroller/childforpreferredverticalbarbehavior
---

# childForPreferredVerticalBarBehavior

Which child view controller, if any, should control the vertical bar behavior.

## Declaration

```swift
var childForPreferredVerticalBarBehavior: UIViewController? { get }
```

## Discussion

Discussion Return a child to defer the configuration to it, or nil to use the configuration provided by this view controller. The system container view controllers forward to their active content by default — UINavigationController to its top view controller, UITabBarController to its selected view controller — so a content view controller’s preference flows up to the window of the app or the nearest presentation.

## See Also

### Configuring bars on the vertical axis

- [preferredVerticalBarBehavior](uikit/uiviewcontroller/preferredverticalbarbehavior.md)
- [UIVerticalBarBehavior](uikit/uiverticalbarbehavior.md)
- [setNeedsUpdateOfVerticalBarConfiguration()](uikit/uiviewcontroller/setneedsupdateofverticalbarconfiguration().md)