Le 20 nov. 2009 à 20:46, Michael de Haan a écrit :
> I am working through an example in Buck/Yacktman's book that uses an
> informal protocol.
>
> In the interface of of a custom class, it is declared as such.
>
>
> #import <Cocoa/Cocoa.h>
>
>
> @interface MyShapeEditorDocument : NSDocument
> {
> ....ivars....
> }
> @end
>
>
> @interface NSObject(MYShapeEditingDocEditor)
>
>
>
> -(void) controllerDidEndEditing;
> @end
>
>
> In the implementation file it is defined, twice, thus.
>
>
> @implementation NSObject(MYShapeEditingDocEditor)
>
> -(void) controllerDidEndEditing
> {
>
> }
> @end
>
> and in the main body of the code, thus.
>
>
> @implementation MyShapeEditorDocument
>
>
> -(void) controllerDidEndEditing
> {
> [[self myView] setNeedsDisplay: YES];
> [[self table] reloadData];
> }
>
>
> Apple's docs say: "When used to declare a protocol, a category interface
> doesn’t have a corresponding implementation. Instead, classes that implement
> the protocol declare the methods again in their own interface files and
> define them along with other methods in their implementation files."
> (http://developer.apple.com/mac/library/documentation/cocoa/Conceptual/ObjectiveC/Articles/ocProtocols.html#//apple_ref/doc/uid/TP30001163-CH15-TPXREF147)
>
>
> What I am not following is the seemingly double definitions. From the docs,
> it would seem that implementation is a 2 step process, not a 3 step as above,
> even though this is clearly correct. What is the essence that I am missing?
The usual way is to NOT implements the NSObject category and test if the
delegate implements the method using -respondsToSelector:
But this way works too if you don't want to have to test before sending your
message.
Anyway, informal protocols are "deprecated" in favor of @protocol with
@optional method.
-- Jean-Daniel
_______________________________________________
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
