---
title: extensionIdentifier
framework: videotoolbox
role: symbol
role_heading: Type Property
path: videotoolbox/vtextensionpropertieskey/extensionidentifier
---

# extensionIdentifier

A dictionary key for the video decoder extension identifier.

## Declaration

```swift
static let extensionIdentifier: VTExtensionPropertiesKey
```

## Discussion

Discussion This key points to a CFStringRef value with the extension identifier, corresponding to the ClassImplementationID value from the EXAppExtensionAttributes dictionary in the Info.plist file.

## See Also

### Keys

- [containingBundleName](videotoolbox/vtextensionpropertieskey/containingbundlename.md)
- [containingBundleURL](videotoolbox/vtextensionpropertieskey/containingbundleurl.md)
- [extensionName](videotoolbox/vtextensionpropertieskey/extensionname.md)
- [extensionURL](videotoolbox/vtextensionpropertieskey/extensionurl.md)