Specifies a filter object used during export to determine which metadata items to transfer from the source asset.
- iOS 7.0+
- macOS 10.9+
- tvOS 9.0+
If the value of this key is
nil, no filter will be applied. This is the default.
The filter will not be applied to metadata set with via the metadata property. To apply the filter to metadata before it is set on the metadata property, see