Circular references and warnings caused by forward declarations in Object C

I have two classes that reference each other and therefore a forward declaratio开发者_运维知识库n is required to avoid circular references. Because of the forward declaration I get all kinds of warnings when trying to reference the class name or properties of the class that has the forward declaration. Any suggestions? The key constraint is I need to preserve the ability to have the classes reference each other

ClassA.h

#import "ClassB.h"

@interface ClassA : NSObject {
    ClassB *class_b;
}
@end

ClassB.h

@class ClassA;

@interface ClassB : NSObject {
     ClassA *class_a;

}

@end

ClassB.m

#import "ClassB.h"


@implementation ClassB

-(void)method{
}
- (id)init
{
    (self = [super init]);
    class_a = [[ClassA alloc] init];
    return self;
}


@end

The warning I get is as follows:

ClassB.m:13: warning: receiver 'ClassA' is a forward class and corresponding @interface may not exist

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In ClassB.m you need to #import "ClassA.h". The @class forward declaration is just for the header file.

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The headers only need to know ClassA and ClassB exist and so a forward declaration works.

However in the implementation they need to know more about the other class. Thus in the implementation files you need to #import the other class. You don't have the an issue as the implementation of one class only needs to know the interface of the other,

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In headers do not use import/include but use the @class directive. It basically tells "there is a class called X defined somewhere"