---
title: "viewWillTransition(to:)"
framework: appkit
role: symbol
role_heading: Instance Method
path: "appkit/nsviewcontroller/viewwilltransition(to:)"
---

# viewWillTransition(to:)

For a view controller that is part of an app extension, called when its view is about to be resized.

## Declaration

```swift
func viewWillTransition(to newSize: NSSize)
```

## Parameters

- `newSize`: The new size for the view controller’s view.

## Discussion

Discussion Override this method if you want to change layout in response to the change in size, potentially in an animated way.

## See Also

### Configuring an App Extension View Controller

- [extensionContext](appkit/nsviewcontroller/extensioncontext.md)
- [preferredScreenOrigin](appkit/nsviewcontroller/preferredscreenorigin.md)
- [preferredMaximumSize](appkit/nsviewcontroller/preferredmaximumsize.md)
- [preferredMinimumSize](appkit/nsviewcontroller/preferredminimumsize.md)
- [sourceItemView](appkit/nsviewcontroller/sourceitemview.md)