kvo

#import <Foundation/Foundation.h>

@interface NameObServer : NSObject


@end


#import "NameObServer.h"

@implementation NameObServer

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
    NSLog(@"%@",keyPath);
    NSLog(@"%@",object);
    NSLog(@"%@",change);
}
@end
====================================
#import <Foundation/Foundation.h>

@interface Student : NSObject

@property(nonatomic,copy) NSString *name;

@end


#import "Student.h"

@implementation Student

-(void)dealloc{
    [_name release];
    [super dealloc];
}
@end


===================================

#import <Foundation/Foundation.h>
#import "Student.h"
#import "NameObServer.h"
int main(int argc, const char * argv[])
{

    @autoreleasepool {
        Student *stu=[[[Student alloc] init] autorelease];
        stu.name=@"mike";
        NameObServer *nameobserve=[[[NameObServer alloc] init] autorelease];
        //在给student的属性name添加观察对象
        [stu addObserver:nameobserve forKeyPath:@"name" options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld context:nil];
        stu.name=@"jack";
        //移除student的属性 name对象
        [stu removeObserver:nameobserve forKeyPath:@"name"];
    
        
    }
    return 0;
}