Pb implementing shared instance

FROM : Kubernan @ 10191 Technologies
DATE : Sat Nov 20 15:18:37 2004

Hello,

After reading the archive mailing list (and some web pages) i'm still
not able
to implement a shared instance (!).
I have a compilation warning and i don't understand why :

    compiling classB.m
   " classA may not respond to '-sharedInstance' "

What i need is to establish a reference of class A in class B.
If you have an idea ...

Here's my code :

   file classA.h
@interface classA : NSObject {

   // other...
}
+(classA *)sharedInstance;
   // other ..
@end

   file classA.m
#import classA.h

@implementation classA
static classA *_sharedInstance = nil;
+(classA *)sharedInstance
{
   static classA *_sharedInstance = nil;
   if (_sharedInstance == nil)
       _sharedInstance = [[self alloc) init];
   return _sharedInstance;
}
@end

I use the shareInstance here :
   file classB.h
#import classA.h
@interface classB : NSObject {
   classA *classARef;
   // other...
}
-(void)setAReferanceToClassA:(classA *)aData;

   file classB.m
#import "classB.h"
@implementation classB
-(void)setAReferanceToClassA:(classA *)aData
{
   classARef = [aData sharedInstance]; // <-- THE COMPIL WARNING (!?)
}
@end

Thanks a lot,
K.