NSNotificationCenter 用法

一個簡單的使用 NSNotificationCenter 的代碼例子

@implementation TestClass


(void) dealloc
{
  // If you don't remove yourself as an observer, the Notification Center
  // will continue to try and send notification objects to the deallocated
  // object.
  [[NSNotificationCenter defaultCenter] removeObserver:self];
  [super dealloc];
}

(id) init
{
  self = [super init];
  if (!self) return nil;
// Add this instance of TestClass as an observer of the TestNotification.
  // We tell the notification center to inform us of "TestNotification"
  // notifications using the receiveTestNotification: selector. By
  // specifying object:nil, we tell the notification center that we are not
  // interested in who posted the notification. If you provided an actual
  // object rather than nil, the notification center will only notify you
  // when the notification was posted by that particular object.
[[NSNotificationCenter defaultCenter] addObserver:self

  selector:@selector(receiveTestNotification:) 
  name:@"TestNotification"
  object:nil];


return self;
}

(void) receiveTestNotification:(NSNotification *) notification
{
  // [notification name] should always be @"TestNotification"
  // unless you use this method for observation of other notifications
  // as well.
if ([[notification name] isEqualToString:@"TestNotification"])

  NSLog (@"Successfully received the test notification!");

}


@end
//... somewhere else in another class ...

(void) someMethod
{
  // All instances of TestClass will be notified
  [[NSNotificationCenter defaultCenter] 
  postNotificationName:@"TestNotification"
  object:self];

}</pre>