NSNotificationCenter的同步和异步

标签：nsnotificationcenter   ios   

首先上代码：

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [button setFrame:CGRectMake(0, 0, 400, 60)];
    [button addTarget:self action:@selector(buttonDown) forControlEvents:UIControlEventTouchUpInside];
    [button setTitle:@"Post Notification" forState:UIControlStateNormal];
    [self.view addSubview:button];
    
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(actionNotification:)
                                                 name:kNotificationName object:nil];
    
}

- (void) actionNotification: (NSNotification*)notification
{
    
    NSString* message = notification.object;
    NSLog(@"%@",message);
    
    sleep(5);
    
    NSLog(@"Action Notification Finish");
    
}

- (void)buttonDown
{
    
    [[NSNotificationCenter defaultCenter] postNotificationName:kNotificationName object:@"object"];
    
    NSLog(@"buttonDown");
    
}

2015-03-17 17:17:59.285 AppTest[16470:169797] object

2015-03-17 17:18:04.285 AppTest[16470:169797] Action Notification Finish

2015-03-17 17:18:04.286 AppTest[16470:169797] buttonDown

异步处理：

方法一：

让通知事件处理方法在子线程中执行，例如：

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        
        sleep(5);
        
    });

方法二：

您可以通过NSNotificationQueue的enqueueNotification:postingStyle:和enqueueNotification:postingStyle:coalesceMask:forModes:方法将通告放入队列，实现异步发送，在把通告放入队列之后，这些方法会立即将控制权返回给调用对象。

我们修改button事件如下：

- (void)buttonDown
{
    NSNotification *notification = [NSNotification notificationWithName:kNotificationName
                                                                 object:@"object"];
    [[NSNotificationQueue defaultQueue] enqueueNotification:notification
                                               postingStyle:NSPostASAP];
    
//    [[NSNotificationCenter defaultCenter] postNotificationName:kNotificationName object:@"object"];
    
    NSLog(@"buttonDown");
    
}

2015-03-17 18:22:05.619 AppTest[18557:195583] buttonDown

2015-03-17 18:22:05.636 AppTest[18557:195583] object

2015-03-17 18:22:10.641 AppTest[18557:195583] Action Notification Finish

NSNotificationCenter的同步和异步

标签：nsnotificationcenter   ios   

原文地址：http://blog.csdn.net/junjun150013652/article/details/44343365