how to block a superclass method to be called to a subclass

- (int)dangerousMethod
{
  [NSException raise:@"Danger!" format:@"Do not call send this method directly to this subclass"];
  return nil;
}

@implementation MyClass
-(void)myMethod:(NSString *)txt{
    if([self class] != [MyClass class]) return;
    NSLog(@"Hello");
}
@end