Question

I have two classes where both of them have protocols to be implemented.

Can I implement one of the class’s protocol in to the other and vice versa?

Does this cause any run time error?

Answer 1

But, I dont suppose this is really necessary. Once you have a delegate implemented then you could send a message to the other class as it the same delegate object. I suppose a simple delegate relations as;

Class A

@protocol ClassAProtocol;
@interface ClassA:NSObject
@property(nonatomic, assign) id<ClassAProtocol> delegate;
@end
@protocol ClassAProtocol <NSObject>
-(void)classA:(ClassA*)classa didSomething:(id)object;
@end

@implementation ClassA
-(void)classAFinishedSomething{
    [self.delegate classA:self didSomething:nil];
    [(ClassB*)self.delegate doSomething];
}

@end

Class B

@interface ClassB : NSObject<ClassAProtocol>
-(void)doSomething;
@end
@implementation ClassB
-(void)doSomething{

} 
-(void)classA:(ClassA*)classa didSomething:(id)object{

}
@end

This will not create a circular reference between the two objects and keep the code clean I suppose. This logic is valid if the delegate is always class B and it respondsToSelector:, the one being sent as a message to class B. But, the above sample posted by matt is mode rigid if you want to have isolate the log between the classes and communicate via standard mechanism.