iOS键盘高度的获取

<pre>

• (void)registerNotification
  {
  [super registerNotification];

  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleKeyboardWillShowNotification:) name:UIKeyboardWillShowNotification object:nil];
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleKeyboardWillChangeFrameNotification:) name:UIKeyboardWillChangeFrameNotification object:nil];
  }

• (void)deregisterNotification
  {
  [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil];
  [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillChangeFrameNotification object:nil];
  [super deregisterNotification];
  }

• (void)handleKeyboardWillShowNotification:(NSNotification)noti
  {
  CGFloat tmpKeyboardVisibleHeight = 0;
  CGRect endRect = [(NSValue)noti.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
  tmpKeyboardVisibleHeight = self.view.height - endRect.origin.y;
  if (tmpKeyboardVisibleHeight != currentKeyboardVisibleHeight)
  {
  currentKeyboardVisibleHeight = tmpKeyboardVisibleHeight;
  [self scollContentContainer:currentKeyboardVisibleHeight];
  }
  }

• (void)handleKeyboardWillChangeFrameNotification:(NSNotification)noti
  {
  //如果currentKeyboardVisibleHeight为0则代表键盘将会被隐藏，否则则会被显示出来
  CGRect endRect = [(NSValue)noti.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
  //不能判断beginRect和endRect是否相等，如果在不相等的时候才做�更新，程序会出现bug
  CGFloat tmpKeyboardVisibleHeight = 0;
  tmpKeyboardVisibleHeight = self.view.height - endRect.origin.y;
  if (tmpKeyboardVisibleHeight != currentKeyboardVisibleHeight)
  {
  currentKeyboardVisibleHeight = tmpKeyboardVisibleHeight;
  //如果密码框可以切换输入法，这儿可能会有潜在的bug
  [self scollContentContainer:currentKeyboardVisibleHeight];
  }
  }
  </pre>