---
title: "tabBarController(_:sidebar:willBeginDisplaying:)"
framework: uikit
role: symbol
role_heading: Instance Method
path: "uikit/uitabbarcontroller/sidebar-swift.class/delegate-swift.protocol/tabbarcontroller(_:sidebar:willbegindisplaying:)"
---

# tabBarController(_:sidebar:willBeginDisplaying:)

Notifies the delegate when the sidebar is about to display the row representing the specified tab

## Declaration

```swift
optional func tabBarController(_ tabBarController: UITabBarController, sidebar: UITabBarController.Sidebar, willBeginDisplaying tab: UITab)
```