A mutable metadata item associated with an audiovisual asset or with one of its tracks.
- iOS 4.0+
- macOS 10.7+
- Mac Catalyst 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
You can initialize a mutable metadata item from an existing
AVMetadata object or with a one or more of the basic properties of a metadata item: a key, a key space, a locale, and a value.