Returns a canonical version of the specified request.
- iOS 2.0+
- macOS 10.2+
- tvOS 9.0+
- watchOS 2.0+
The request whose canonical version is desired.
The canonical form of
It is up to each concrete protocol implementation to define what “canonical” means. A protocol should guarantee that the same input request always yields the same canonical form.
Special consideration should be given when implementing this method, because the canonical form of a request is used to lookup objects in the URL cache, a process which performs equality checks between
This is an abstract method and subclasses must provide an implementation.