Objective-c:How can the object p know the changes of Person class after Person class is changed? -

how can object p know content of person class changed ?like this:

before person class changed:

#import <foundation/foundation.h> @interface person:nsobject  @end  int main(){     person *p = [[person alloc] init];     return 0;  } 

after person class changed:

#import <foundation/foundation.h> @interface person:nsobject @property int age;/* add new member */ - (void)test;     /* add new method */ @end @implememtation person - (void)test {    nslog(@"hello"); } @end  int main(){      person *p = [[person alloc] init];      return 0; } 

how can object p know person added new member , new method?

use instruments , allocations template , enter "person" in search box. if person object presently in memory in list.