NSURLProtocol

An NSURLProtocol object handles the loading of protocol-specific URL data.

@abstract This method registers a protocol class, making it visible

to several other NSURLProtocol class methods.

@discussion When the URL loading system begins to load a request,

each protocol class that has been registered is consulted in turn to

see if it can be initialized with a given request. The first

protocol handler class to provide a YES answer to

<tt>+canInitWithRequest:</tt> "wins" and that protocol

implementation is used to perform the URL load. There is no

guarantee that all registered protocol classes will be consulted.

Hence, it should be noted that registering a class places it first

on the list of classes that will be consulted in calls to

<tt>+canInitWithRequest:</tt>, moving it in front of all classes

that had been registered previously.

<p>A similar design governs the process to create the canonical form

of a request with the <tt>+canonicalRequestForRequest:</tt> class

method.

@param protocolClass the class to register.

@result YES if the protocol was registered successfully, NO if not.

The only way that failure can occur is if the given class is not a

subclass of NSURLProtocol.