通知机制

Sian

通知是一种设计模式，与代理有类似的地方，一般实现分为几个步骤

1、设置监听

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(recive:) name:@"notification" object:nil];

2、发送通知

        NSDictionary *dic = [NSDictionary dictionaryWithObject:@"value" forKey:@"key"];
   
        [[NSNotificationCenter defaultCenter] postNotificationName:@"notification" object:nil userInfo:dic];

3、通知响应

        - (void)recive:(NSDictionary *)userInfo
        {
                    NSLog(@"%@", userInfo);
        }

示例：

1. @implementation SAViewController
3. -(id)init
4. {
5.     if (self = [super init]){
6.         self.view.backgroundColor = [UIColor whiteColor];
7.         
8.         // 1、设置监听
9.         [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(recive:) name:@"notification" object:nil];
10.         
11.         // 创建一个按钮，当按钮点击时触发通知发送事件
12.         UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
13.         button.frame = CGRectMake(10, 50, 50, 30);
14.         [button setTitle:@"abc" forState:UIControlStateNormal];
15.         [self.view addSubview:button];
16.         [button addTarget:self action:@selector(buttonClick) forControlEvents:UIControlEventTouchUpInside];
17.     }
18.     return self;
19. }
21. - (void)buttonClick
22. {
23.    
24.     // 2、发送通知
25.     NSDictionary *dic = [NSDictionary dictionaryWithObject:@"value" forKey:@"key"];
26.    
27.     [[NSNotificationCenter defaultCenter] postNotificationName:@"notification" object:nil userInfo:dic];
29. }
31. // 3、通知响应
32. - (void)recive:(NSDictionary *)userInfo
33. {
34.     NSLog(@"%@", userInfo);
35. }
36. @end

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