AVAsset object encapsulates information about a resource request issued from a resource loader object.
- iOS 6.0+
- macOS 10.9+
- tvOS 9.0+
AVURLAsset object needs help loading a resource, it asks its
AVAsset object to assist. The resource loader encapsulates the request information by creating an instance of this object, which it then hands to its delegate object for processing. The delegate uses the information in this object to perform the request and report on the success or failure of the operation.