---
title: "VTSessionCopySupportedPropertyDictionary(_:supportedPropertyDictionaryOut:)"
framework: videotoolbox
role: symbol
role_heading: Function
path: "videotoolbox/vtsessioncopysupportedpropertydictionary(_:supportedpropertydictionaryout:)"
---

# VTSessionCopySupportedPropertyDictionary(_:supportedPropertyDictionaryOut:)

Retrieves a dictionary enumerating all the supported properties of a video toolbox session.

## Declaration

```swift
func VTSessionCopySupportedPropertyDictionary(_ session: VTSession, supportedPropertyDictionaryOut: UnsafeMutablePointer<CFDictionary?>) -> OSStatus
```

## Parameters

- `session`: The session object.
- `supportedPropertyDictionaryOut`: A pointer to a doc://com.apple.documentation/documentation/CoreFoundation/CFDictionary.

## Discussion

Discussion The keys of the returned dictionary are the supported property keys. The values are themselves dictionaries, each containing the following optional fields: The type of value (kVTPropertyTypeKey) The read/write status of the property (kVTPropertyReadWriteStatusKey) Whether the property is suitable for serialization (kVTPropertyShouldBeSerializedKey) A range or list of the supported values, if appropriate Developer-level documentation for the property (kVTPropertyDocumentationKey) The caller must release the returned dictionary.

## See Also

### Getting Properties

- [VTSessionCopyProperty(_:key:allocator:valueOut:)](videotoolbox/vtsessioncopyproperty(_:key:allocator:valueout:).md)
- [VTSessionCopySerializableProperties(_:allocator:dictionaryOut:)](videotoolbox/vtsessioncopyserializableproperties(_:allocator:dictionaryout:).md)
- [Supported Property Dictionary Constants](videotoolbox/supported-dictionary-constants.md)