iPhone获取键盘高度，通报方式隐藏和显示键盘

iPhone获取键盘高度，通知方式隐藏和显示键盘
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasShown:) name:UIKeyboardDidShowNotification object:nil];
   
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasHidden:) name:UIKeyboardDidHideNotification object:nil];


- (void) keyboardWasShown:(NSNotification *) notif{
    NSDictionary *info = [notif userInfo];
    NSValue *value = [info objectForKey:UIKeyboardFrameBeginUserInfoKey];
    CGSize keyboardSize = [value CGRectValue].size;

    NSLog(@"keyBoard:%f", keyboardSize.height);  //216
    keyboardWasShown = YES;
}

- (void) keyboardWasHidden:(NSNotification *) notif{
    NSDictionary *info = [notif userInfo];
   
    NSValue *value = [info objectForKey:UIKeyboardFrameBeginUserInfoKey];
    CGSize keyboardSize = [value CGRectValue].size;
   NSLog(@"keyboardWasHidden keyBoard:%f", keyboardSize.height);
    keyboardWasShown = NO;
   
}