NSURLHandle 0.1 28 February, 2000 NSURLHandle Foundation/NSURLHandle.h

An NSURLHandle instance is used to manage the resource data corresponding to an NSURL object. A single NSURLHandle can be used to manage multiple NSURL objects as long as those objects all refer to the same resource.

Different NSURLHandle subclasses are used to manage different types of URL (usually based on the scheme of the URL), and you can register new subclasses to extend (or replace) the standard ones.

URLHandleClassForURL: anURL Returns the most recently registered NSURLHandle subclass that responds to canInitWithURL: with YES. If there is no such subclass, returns nil. cachedHandleForURL: anURL Returns a previously created object that handles the specified URL (if any exists), otherwise returns nil. canInitWithURL: anURL Implemented by subclasses to say which URLs they can handle. This method is used to determine which subclasses can be used to handle a particular URL. registerURLHandleClass: anURLHandleSubclass Used to register a subclass as being available to handle URLs. addClient: client Adds an object conforming to the NSURLHandleClient protocol as a client of the URL handle. availableResourceData Returns the resource data that is currently available for the handle. This may be a partially loaded resource or may be empty of no data has been loaded yet. backgroundLoadDidFailWithReason: reason This method should be called when a background load fails. The method passes the failure notification to the clients of the handle - so subclasses should call super's implementation at the end of their implementation of this method. beginLoadInBackground This method is called by when a background load begins. Subclasses should call super's implementation at the end of their implementation of this method. cancelLoadInBackground This method should be called to cancel a load currently in progress. The method calls endLoadInBackground Subclasses should call super's implementation at the end of their implementation of this method. didLoadBytes: newBytes loadComplete: yorn This method must be called by subclasses whenever data is loaded. endLoadInBackground This method is called to stop any background loading process. cancelLoadInBackground uses this method to cancel loading. Subclasses should call super's implementation at the end of their implementation of this method. failureReason Returns the failure reason for the last failure to load the resource data. flushCachedData Flushes any cached resource data. initWithURL: url cached: yesno Initialises a handle with the specified URL. The flag determines whether the handle will cache resource data and respond to requests from equivalent URLs for the cached data. loadInBackground Starts (or queues) loading of the handle's resource data in the background (asynchronously). loadInForeground Loads the handle's resource data in the foreground (synchronously). This may be implemented by starting a background load and waiting for it to complete. propertyForKey: propertyKey Returns the property for the specified key, or nil if the key does not exist. propertyForKeyIfAvailable: propertyKey Returns the property for the specified key, but only if the handle does not need to do any work to retrieve it. removeClient: client Removes an object from them list of clients notified of resource loading events by the URL handle. resourceData Returns the resource data belonging to the handler. Calls loadInForeground if necessary. status Returns the current status of the handle. writeData: data Writes resource data to the handle. Returns YES on success, NO on failure. writeProperty: propertyValue Attempts to set property for handle. Foundation/NSURLHandle.h URLHandleResourceDidBeginLoading: sender Sent by the NSURLHandle object when it begins loading resource data. URLHandleResourceDidCancelLoading: sender Sent by the NSURLHandle object when resource loading is cancelled by programmatic request (rather than by failure). URLHandleResourceDidFinishLoading: sender Sent by the NSURLHandle object when it completes loading resource data. URLHandle: sender resourceDidBecomeAvailable: data Sent by the NSURLHandle object when some data becomes available from the handle. URLHandle: sender resourceDidFailLoadingWithReason: reason Sent by the NSURLHandle object on resource load failure. Supplies a human readable failure reason. int Foundation/NSURLHandle.h An NSURLHandleStatus is used to report the current state of an NSURLHandle object, it can take the following values - NSURLHandleNotLoaded NSURLHandleLoadSucceeded NSURLHandleLoadInProgress NSURLHandleLoadFailed