---
title: "pdfViewWillChangeScaleFactor(_:toScale:)"
framework: pdfkit
role: symbol
role_heading: Instance Method
path: "pdfkit/pdfviewdelegate/pdfviewwillchangescalefactor(_:toscale:)"
---

# pdfViewWillChangeScaleFactor(_:toScale:)

Overrides changes to the scale factor.

## Declaration

```swift
optional func pdfViewWillChangeScaleFactor(_ sender: PDFView, toScale scaler: CGFloat) -> CGFloat
```