监听键盘弹出 iOS

//增加监听，当键盘出现或改变时收出消息
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification
object:nil];
//增加监听，当键退出时收出消息
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:nil];

//当键盘出现或改变时调用

• (void)keyboardWillShow:(NSNotification *)aNotification {
  //获取键盘的高度
  NSDictionary *userInfo = [aNotification userInfo];
  NSValue *aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
  CGRect keyboardRect = [aValue CGRectValue];
  int height = keyboardRect.size.height;
  // 需要进行的操作
  }
  //当键退出时调用
• (void)keyboardWillHide:(NSNotification *)aNotification {
  // 界面复原
  }