Provides the metadata identifier that’s equivalent to a key and key space.
- iOS 8.0+
- macOS 10.10+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
The metadata key.
The metadata key space.
A metadata identifier equivalent to
nil if no identifier can be constructed
Metadata keys that are not instances of
NSData cannot be converted to metadata identifiers; they also cannot be written to media resources via
AVAsset. Metadata item
key must be a string of one to four printable ASCII characters.
For custom identifiers, the
AVMetadata is recommended. This
key defines its key values to be expressed as reverse-DNS strings, which allows third parties to define their own keys in a well established way that avoids collisions.