对象p如何知道Person类的内容是否已更改?像这样:
在Person类改变之前:
#import <Foundation/Foundation.h>
@interface Person:NSObject
@end
int main(){
Person *p = [[Person alloc] init];
return 0;
}
Person类更改后:
#import <Foundation/Foundation.h>
@interface Person:NSObject
@property int age;/* add a new member */
- (void)test; /* add a new method */
@end
@implememtation Person
- (void)test
{
NSLog(@"Hello");
}
@end
int main(){
Person *p = [[Person alloc] init];
return 0;
}
对象p如何知道Person添加了新成员和新方法?