Returns an immutable dictionary containing all the extensions of a CMFormatDescription.


func CMFormatDescriptionGetExtensions(_ desc: CMFormatDescription) -> CFDictionary?



CMFormatDescription being interrogated

Return Value

An immutable dictionary containing all the extensions of the CMFormatDescription. May be NULL.


If there are no extensions, NULL is returned. Extensions dictionaries are valid property list objects. This means that dictionary keys are all CFStrings, and the values are all either CFNumber, CFString, CFBoolean, CFArray, CFDictionary, CFDate, or CFData. The returned dictionary is not retained by this call, so clients are required to retain it if they need to keep it longer.

See Also

Common Functions

func CMFormatDescriptionCreate(allocator: CFAllocator?, mediaType: CMMediaType, mediaSubType: FourCharCode, extensions: CFDictionary?, formatDescriptionOut: UnsafeMutablePointer<CMFormatDescription?>) -> OSStatus

Creates a generic CMFormatDescription object. You should not call this method for the media types that has specific create functions such as audio, video, text, muxed, metaData and timeCode.

func CMFormatDescriptionEqualIgnoringExtensionKeys(CMFormatDescription?, otherFormatDescription: CMFormatDescription?, extensionKeysToIgnore: CFTypeRef?, sampleDescriptionExtensionAtomKeysToIgnore: CFTypeRef?) -> Bool

Compares two CMFormatDescription objects for equality, ignoring differences in the specified lists of format description extension keys and sample description extension keys.

func CMFormatDescriptionGetMediaSubType(CMFormatDescription) -> FourCharCode

Returns the media subtype of a CMFormatDescription.

func CMFormatDescriptionGetMediaType(CMFormatDescription) -> CMMediaType

Returns the media type of a CMFormatDescription.

func CMFormatDescriptionGetTypeID() -> CFTypeID

Returns the CFTypeID of CMFormatDescription objects.