Informal Protocol In objective-C?

Question

I was wondering if someone can explain what is informal protocols in Objective C? I try to understand it on apple documentation and some other books but my head is still spi

Answer 1

Based on "Jonathan Sterling" answer, can i say the following code represent informal protocol?

Apple documentation:

"When used to declare a protocol, a category interface doesn’t have a corresponding implementation. Instead, classes that implement the protocol declare the methods again in their own interface files and define them along with other methods in their implementation files."

#import 

@interface Cat1 : NSObject {


}
- (void) simpleMethod;

@end

@implementation Cat1

- (void) simpleMethod
{

    NSLog(@"Simple Method");
}

@end


@interface Cat1 (Cat2) 
- (void) addingMoreMethods;

@end




@interface MYClass : Cat1

@end

@implementation MYClass

- (void) addingMoreMethods
{
    NSLog(@"Testing!");
}
@end

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];


    MYClass *myclass = [[MYClass alloc] init];
    [myclass addingMoreMethods];
    [myclass release];
    [pool drain];
    return 0;
}