Why does NSDictionary report an unusual class name?

Question

NSDictionary *dict = [NSDictionary dictionary];
NSLog(@\"%@\", NSStringFromClass([dict class])); 

This code prints \"__NSDictionary0\".

For my

Answer 1

For an NSDictionary mutability test, could't you just to a 'respondsToSelector' for a method that only an NSMutableDictionary would have, like addObject:ForKey:?