Provides data to the loading request.
- iOS 7.0+
- macOS 10.9+
- Mac Catalyst 13.0+Beta
- tvOS 9.0+
An instance of NSData containing some or all of the requested bytes.
This method may be invoked multiple times on the same instance of
AVAsset to provide the full range of requested data incrementally. Upon each invocation, the value of the
current property is updated to match the amount of data provided.