//注册键盘出现的通知        [[NSNotificationCenter defaultCenter] addObserver:self                                                 selector:@selector(keyboardWasShown:)                                                     name:UIKeyboardWillShowNotification object:nil];        //注册键盘消失的通知        [[NSNotificationCenter defaultCenter] addObserver:self                                                 selector:@selector(keyboardWillBeHidden:)                                                     name:UIKeyboardWillHideNotification object:nil];    - (void)keyboardWasShown:(NSNotification*)aNotification    {        //键盘高度        CGRect keyBoardFrame = [[[aNotification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];    }      -(void)keyboardWillBeHidden:(NSNotification*)aNotification    {      }