Returns whether a request can be handled based on a preflight evaluation.
- iOS 2.0+
- macOS 10.2+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
The request to evaluate. The connection deep-copies the request on creation.
true if a preflight operation determines that a connection with
request can be created and the associated I/O can be started,
The result of this method is valid as long as no
URLProtocol classes are registered or unregistered, and
request remains unchanged. Applications should be prepared to handle failures even if they have performed request preflighting by calling this method.