ios通知-kvo

   // KVC: Key Value Coding, 常见作用：给模型属性赋值
    // KVO: Key Value Observing, 常用作用：监听模型属性值的改变

//
//  ViewController.m
//  11-通知、KVO、代理
//
//  Created by xiaomage on 15/6/6.
//  Copyright (c) 2015年 xiaomage. All rights reserved.
//

#import "ViewController.h"
#import "XMGPerson.h"

@interface ViewController ()
@property (nonatomic, strong) XMGPerson *p1;
@property (nonatomic, strong) XMGPerson *p2;
@property (nonatomic, strong) XMGPerson *p3;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
//    self.p1 = [[XMGPerson alloc] init];
//    self.p1.name = @"p1";
//    
//    self.p2 = [[XMGPerson alloc] init];
//    self.p2.name = @"p2";
//    
//    self.p3 = [[XMGPerson alloc] init];
//    self.p3.name = @"p3";
//    同一个通知TestNotification可以被多个对象person监听
// 当收到TestNotification通知就调用self.p1的test方法
//    [[NSNotificationCenter defaultCenter] addObserver:self.p1 selector:@selector(test) name:@"TestNotification" object:nil];
//    [[NSNotificationCenter defaultCenter] addObserver:self.p2 selector:@selector(test) name:@"TestNotification" object:nil];
//    [[NSNotificationCenter defaultCenter] addObserver:self.p3 selector:@selector(test) name:@"TestNotification" object:nil];
//    多个对象可以发出同一个通知
//对象@“123”发出TestNotification通知
//    [[NSNotificationCenter defaultCenter] postNotificationName:@"TestNotification" object:@"123"];
//    [[NSNotificationCenter defaultCenter] postNotificationName:@"TestNotification" object:@"345"];
    
    // KVC: Key Value Coding, 常见作用：给模型属性赋值
    // KVO: Key Value Observing, 常用作用：监听模型属性值的改变
    
    
    self.p1 = [[XMGPerson alloc] init];
    self.p1.name = @"p1";
    //self.p1 监听属性 name的改变，NSKeyValueObservingOptionOld表示监听方法中的NSDictional显示旧值
    [self.p1 addObserver:self forKeyPath:@"name" options: NSKeyValueObservingOptionOld context:nil];
    
    self.p1.name = @"pppp1";
}
//所有的通知监听 都要在dealloc销毁时removeObserver
- (void)dealloc
{
    [self.p1 removeObserver:self forKeyPath:@"name"];
}

#pragma mark - KVO监听方法
/**
 * 当监听到object的keyPath属性发生了改变
*这个方法是NSObject的类扩展方法，用来监听对象属性改变
*keyPath属性名称如name
*id 对象 如self.p1
*change 记录改变前后的值
 */
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    NSLog(@"监听到%@对象的%@属性发生了改变， %@", object, keyPath, change);
}

@end