On Fri, Nov 5, 2010 at 9:36 AM, Dan Hopwood <d...@biasdevelopment.com> wrote: > > I am using XML-RPC technology to invoke a website back end. I used the > Wordpress project to extract what I needed in order to send off requests and > decode what I get back from the webservice. This works. > > The encoding/decoding methods equate the *struct* tag to the type * > NSDictionary* for obvious reasons. In order to form the NSDictionary object > to encode however requires me to set the name value pairs manually, which is > annoying. I wondered whether it's possible to instead define a custom class, > which contains the attributes I want to send and then cast the object to > type NSDictionary, which the encoder is then able to interpret. > > In the same way, if a struct is returned by the webservice I'd like to be > able to cast the NSDictionary object to a custom class.
If I understand your question correctly, then no, a type cast won't do what you want. Casting an Objective-C object is a compile-time construct that tells the compiler to assume that an object is of the specified type, to avoid warnings about unknown messages. But it does *not* actually convert the object - that is, it has absolutely no effect at run time. An object is what it is, regardless of any type casting. What you could do instead is extend NSDictionary with a "convenience constructor" class method. Similarly, you could create an instance method that would return an instance of your custom class from a dictionary. @interface NSDictionary (MyWordpressExtensions) +(NSDictionary*) dictionaryWithMyCustomObject:(MyCustomObject *)obj; - (MyCustomObject *) customObject; @end True, you'd still need to write the necessary conversion code manually - but you'd only need to do so once, and it wouldn't clutter up your code outside of these methods. You'd use a different syntax to do the conversion, but it would be just as brief and easy to read as your proposed type cast. Assuming that you have a "wordpress" object that returns an NSDictionary from -getResponse, the type casting you propose might look like this: // Hypothetical conversion by type cast, WILL NOT WORK! MyCustomObject *obj = (MyCustomObject*)[wordpress getResponse]; The alternative, using a category method such as the above to do the conversion, would look like this: MyCustomObject *obj = [[wordpress getResponse] customObject]; sherm-- -- Cocoa programming in Perl: http://camelbones.sourceforge.net _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
