---
title: "session(_:didChangeViewRotationAngle:)"
framework: arkit
role: symbol
role_heading: Instance Method
platforms: [iOS 27.0+, iPadOS 27.0+]
path: "arkit/arsessionobserver/session(_:didchangeviewrotationangle:)"
---

# session(_:didChangeViewRotationAngle:)

This is called when the view rotation angle changes.

## Declaration

```swift
optional func session(_ session: ARSession, didChangeViewRotationAngle viewRotationAngle: CGFloat)
```

## Parameters

- `session`: The session that provides the angle.
- `viewRotationAngle`: The angle, in degrees, normalized to [0, 360) (0 at LandscapeRight, 90 at Portrait, 180 at LandscapeLeft, and 270 at PortraitUpsideDown).

## Discussion

Discussion ARKit calls this method when a new angle becomes available, in step with the system UI rotation. Implement it to rotate a view by the given angle so the ARFrame it displays stays level with the horizon as the device rotates.