---
title: "willApplyChanges(_:)"
framework: spatialpreview
role: symbol
role_heading: Instance Method
platforms: [macOS 27.0+]
path: "spatialpreview/usdpreviewsession/changelistdelegate/willapplychanges(_:)"
---

# willApplyChanges(_:)

## Declaration

```swift
@MainActor func willApplyChanges(_ event: USDPreviewSession.Event)
```

## See Also

### Deprecated

- [didApplyChanges(_:)](spatialpreview/usdpreviewsession/changelistdelegate/didapplychanges(_:).md)