Re: How to adopt a superclass's protocol?
Re: How to adopt a superclass's protocol?
- Subject: Re: How to adopt a superclass's protocol?
- From: "K. Darcy Otto" <email@hidden>
- Date: Tue, 29 Apr 2008 13:40:43 -0700
The casting worked, and the protocol gets found; but I'm still getting
a warning that the protocol is not found. Here's what I have:
Superclass.h:
@protocol Check;
Superclass.m:
@protocol Check
@optional
-(BOOL)optionalMethodToImplement;
@end
(I'm relegating the protocol to the .m file to make it "private" in a
sense.)
Subclass.h
@interface Subclass : Superclass <Check>
...
Now, the compiler issues a warning at the @interface line in
Subclass.h - "no definition of protocol 'Check' is found". But it is
clear that the protocol is being located at runtime nevertheless,
because if I eliminate <Check> from the @interface line,
optionalMethodToImplement: does not get called. Also, what is
interesting is that if I move @protocol Check ... @end in Superclass.m
to Superclass.h, the warning goes away. So, is there a way to keep
@protocol Check ... @end in Superclass.m and eliminate the warning?
Thanks.
On 28-Apr-08, at 11:25 PM, Michael Vannorsdel wrote:
You can make the superclass's method look like this:
- (void)doSomething
{
if([self conformsToProtocol:@protocol(Check)])
[(SuperClass <Check> *)self optionalMethodToImplement];
}
The cast eliminates the compiler warning.
As far as making it private it depends what you mean by that. If
you don't want it visible in headers you're going to distribute you
can put:
@protocol Check;
in the public header then actually define the whole protocol in a
private undistributed header.
On Apr 28, 2008, at 9:22 PM, K. Darcy Otto wrote:
Okay, I have done this, and things are compiling and running
correctly. Thank you. Two additional questions then. First, I
still get the warning that the superclass "may not respond" to the
method (and to be sure, it is only implemented in the subclass, but
the superclass calls it after a conformsToProtocol: check).
Second, I would like the optionalMethodToImplement to be private -
usually I put this in the .m file under a category; but when I do
that with the protocol, the subclass cannot locate the protocol.
Any suggestions?
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