---
title: "beginAppearanceTransition(_:animated:)"
framework: uikit
role: symbol
role_heading: Instance Method
path: "uikit/uiviewcontroller/beginappearancetransition(_:animated:)"
---

# beginAppearanceTransition(_:animated:)

Tells a child controller its appearance is about to change.

## Declaration

```swift
func beginAppearanceTransition(_ isAppearing: Bool, animated: Bool)
```

## Parameters

- `isAppearing`: doc://com.apple.documentation/documentation/Swift/true if the child view controller’s view is about to be added to the view hierarchy, doc://com.apple.documentation/documentation/Swift/false if it is being removed.
- `animated`: If doc://com.apple.documentation/documentation/Swift/true, the transition is being animated.

## Discussion

Discussion If you are implementing a custom container controller, use this method to tell the child that its views are about to appear or disappear. Do not invoke viewWillAppear(_:), viewWillDisappear(_:), viewDidAppear(_:), or viewDidDisappear(_:) directly.

## See Also

### Managing child view controllers in a custom container

- [children](uikit/uiviewcontroller/children.md)
- [addChild(_:)](uikit/uiviewcontroller/addchild(_:).md)
- [removeFromParent()](uikit/uiviewcontroller/removefromparent().md)
- [transition(from:to:duration:options:animations:completion:)](uikit/uiviewcontroller/transition(from:to:duration:options:animations:completion:).md)
- [shouldAutomaticallyForwardAppearanceMethods](uikit/uiviewcontroller/shouldautomaticallyforwardappearancemethods.md)
- [endAppearanceTransition()](uikit/uiviewcontroller/endappearancetransition().md)
- [hierarchyInconsistencyException](uikit/uiviewcontroller/hierarchyinconsistencyexception.md)