---
title: "VTSessionSetProperty(_:key:value:)"
framework: videotoolbox
role: symbol
role_heading: Function
path: "videotoolbox/vtsessionsetproperty(_:key:value:)"
---

# VTSessionSetProperty(_:key:value:)

Sets a property on a VideoToolbox session.

## Declaration

```swift
func VTSessionSetProperty(_ session: VTSession, key propertyKey: CFString, value propertyValue: CFTypeRef?) -> OSStatus
```

## Discussion

Discussion Setting a property value to NULL restores the default value.

## Topics

### Related Documentation

- [Compression Properties](videotoolbox/compression-properties.md)
- [Decompression Properties](videotoolbox/decompression-properties.md)
- [Pixel Transfer Properties](videotoolbox/pixel-transfer-properties.md)

## See Also

### Setting Properties

- [VTSessionSetProperties(_:propertyDictionary:)](videotoolbox/vtsessionsetproperties(_:propertydictionary:).md)