conformsToProtocol

gistfile1.m

    int class_count = objc_getClassList(nil, 0);
    Class *buffer = calloc(class_count, sizeof(Class)); 
    if (buffer) {      
        //NSLog(@"allocated a %d bytes buffer",malloc_size(buffer));        
        objc_getClassList(buffer,class_count);        
        //NSLog(@"total %i classes",class_count);        
        for (int i = 0; i < class_count; ++i) {          
            Class currClass = buffer[i];
            if ( class_respondsToSelector(currClass, @selector(conformsToProtocol:)) ) {        
                if ([currClass conformsToProtocol:@protocol(NSMutableCopying)]) {
                    NSString *className = NSStringFromClass(currClass);
                    NSLog(@"%@",className);                        
                }
            } 
        }
        free(buffer);        
    }