AVAssetResourceLoadingDataRequest
An object for requesting data from a resource that an asset resource-loading request references.
Declaration
class AVAssetResourceLoadingDataRequestOverview
The AVAssetResourceLoaderDelegate uses the AVAssetResourceLoadingDataRequest class to do the actual data reading, and its methods will be invoked, as necessary, to acquire data for the AVAssetResourceLoadingRequest instance.
When the resource loading delegate, which implements the AVAssetResourceLoaderDelegate protocol, receives an instance of AVAssetResourceLoadingRequest as the second parameter of the delegate’s resourceLoader(_:shouldWaitForLoadingOfRequestedResource:) method, it has the option of accepting responsibility for loading the referenced resource. If it accepts that responsibility, by returning true, it must check whether the dataRequest property of the AVAssetResourceLoadingRequest instance is not nil. If it is not nil, the resource loading delegate is informed of the range of bytes within the resource that are required by the underlying media system. In response, the data is provided by one or more invocations of respond(with:) as required to provide the requested data. The data can be provided in increments determined by the resource loading delegate according to convenience or efficiency.
When the AVAssetResourceLoadingRequest method finishLoading() is invoked, the data request is considered fully satisfied. If the entire range of bytes requested has not yet been provided, the underlying media system assumes that the resource’s length is limited to the provided content.