註冊通知:即要在什麼地方接受訊息

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

           [[NSNotificationCenter defaultCenter] postNotificationName:@"mytest"　object:searchFriendArray]；

   object：傳遞的引數

- (void) mytest:(NSNotification*) notification

{

   id obj = [notification object];//獲取到傳遞的物件

} 

2~移除某個通知

    [[NSNotificationCenterdefaultCenter] removeObserver:selfname:UIKeyboardWillShowNotificationobject:nil];