可可的定义通知的例子

Question

有人可以请告诉我一个例子的一个可可Obj-C对象，一个自定义的通知，如何火，订阅这，并处理它？

Answer 1

@implementation MyObject

// Posts a MyNotification message whenever called
- (void)notify {
  [[NSNotificationCenter defaultCenter] postNotificationName:@"MyNotification" object:self];
}

// Prints a message whenever a MyNotification is received
- (void)handleNotification:(NSNotification*)note {
  NSLog(@"Got notified: %@", note);
}

@end

// somewhere else
MyObject *object = [[MyObject alloc] init];
// receive MyNotification events from any object
[[NSNotificationCenter defaultCenter] addObserver:object selector:@selector(handleNotification:) name:@"MyNotification" object:nil];
// create a notification
[object notify];

更多信息，请参阅的文档 NSNotificationCenter.

Answer 2

步骤1：

//register to listen for event    
[[NSNotificationCenter defaultCenter]
  addObserver:self
  selector:@selector(eventHandler:)
  name:@"eventType"
  object:nil ];

//event handler when event occurs
-(void)eventHandler: (NSNotification *) notification
{
    NSLog(@"event triggered");
}

步骤2：

//trigger event
[[NSNotificationCenter defaultCenter]
    postNotificationName:@"eventType"
    object:nil ];

Answer 3

一定要注销的通知(观察员)当你的目的是释放。苹果文件指出："以前的对象是观察通知被释放，就必须告诉通知中心，以阻止它发送通知"。

对于本地通知下一代码是适用的：

[[NSNotificationCenter defaultCenter] removeObserver:self];

和观察员的分布通知：

[[NSDistributedNotificationCenter defaultCenter] removeObserver:self];