On Mar 15, 2010, at 3:49 PM, Jeff Laing wrote:
> But my protocol only wanted to define the methods in my protocol - a nice
> clean Interface definition that's independent of all other definitions.
> After all, Apple might add some non-optional methods to NSObject (ok, that's
> unlikely) that all objects implementing my protocol would suddenly fail to
> compile on.
Unless you are going to be working with objects that don't descend from
NSObject (the class) then extending NSObject (the protocol) should not be an
issue. From the documentation on the NSObject Protocol:
"The NSObject protocol groups methods that are fundamental to all Objective-C
objects.
If an object conforms to this protocol, it can be considered a first-class
object. Such an object can be asked about its:
• Class, and the place of its class in the inheritance hierarchy
• Conformance to protocols
• Ability to respond to a particular message
In addition, objects that conform to this protocol—with its retain, release,
and autorelease methods—can also integrate with the object management and
deallocation scheme defined in Foundation (for more information see, for
example, Memory Management Programming Guide for Cocoa). Thus, an object that
conforms to the NSObject protocol can be managed by container objects like
those defined by NSArray and NSDictionary.
The Cocoa root class, NSObject, adopts this protocol, so all objects inheriting
from NSObject have the features described by this protocol."
On a practical note, many of the protocols that you work with in Cocoa and
Cocoa Touch also declare that they extend NSObject, so this assumption has
already been made for you in many places.
--
David Duncan
Apple DTS Animation and Printing
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