iOS-NSNotificationCenter通知中心是同步操

前言

最近有个小伙伴到喜马拉雅去面试，面试官问他一个问题就是“通知中心是同步操作还是异步操作？”，小伙伴回答成异步了，然后就是回家等消息，然后就是没有然后了。。。

我先举几个小的列子给大家瞅瞅：

• (void)sentValueBtnClick:(UIButton *)button{
  NSLog(@"发送通知");
  NSDictionary *dict = @{@"myValue":@"ZFJ通知传值"};
  [[NSNotificationCenter defaultCenter] postNotification:[NSNotification notificationWithName:@"KPassValue" object:nil userInfo:dict]];
  }

• (void)viewDidLoad {
  [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.
  _textField.layer.borderColor = [UIColor redColor].CGColor;
  _textField.layer.borderWidth = 1.0;

  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(passValue:) name:@"KPassValue" object:nil];
  }

• (void)passValue:(NSNotification *)text{
  NSString *valueStr = text.userInfo[@"myValue"];
  NSLog(@"收到值：%@",valueStr);
  sleep(3);
  self.textField.text = valueStr;
  NSLog(@"通知赋值完毕");

https://blog.csdn.net/u014220518/article/details/70598063