iPhone-向任何收听者对象“空中”发送消息

/* Subscribe to be sent -noteThis:
 * whenever a notification named @\"NotificationName\" is posted to the center
 * with any (or no) object. */
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc addObserver:self selector:@selector(noteThis:)
           name:@\"NotificationName\"
         object:nil];

/* Post a notification. */
[nc postNotificationName:@\"NotificationName\" object:self userInfo:someDict];

/* Handle a notification. */
- (void)noteThis:(NSNotification *)note
{
   id object = [note object];
   NSDictionary *userInfo = [note userInfo];
   /* take some action */
}

NSNotificationCenter

#define kNotificationCenter [NSNotificationCenter defaultCenter]
#define kNotificationToSend @\"a notification name as a string\"

//... Post the notification 

[kDefaultCenter postNotificationNamed:knotificationToSend withObject:nil];

[kNotificationCenter addObserver:self selector:@selector(methodToHandleNotification) object:nil];

//... Usually in the dealloc or willDisappear method:

[kNotificationCenter removeObserver:self];

NSNotification *notificationObj;
NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
[center postNotification:notificationObj];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(method:) object:nil];

method:

NSNotification

[notificationObj object

[notificationObj userInfo]

notificationObj

NSNotificationCenter

NSNotification