copyFormatDescription()
Creates a format description based on the receiver’s items.
Declaration
func copyFormatDescription() -> CMMetadataFormatDescription?Return Value
An instance of CMMetadataFormatDescription sufficient to describe the contents of all the items referenced by the object.
Discussion
The returned format description is suitable for use as the format hint parameter when creating an instance of AVAssetWriterInput.
Each item referenced by the receiver must carry a non-nil value for its dataType property. An exception will be thrown if any item does not have a data type.