在开发中经常用到监听键盘的弹出弹入，并据此进行一些操作。
1.注册监听
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyBoardWillShow:) name:UIKeyboardWillShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyBoardWillHide:) name:UIKeyboardWillHideNotification object:nil];
2.根据监听获取键盘的高度，以此进行后续一下操作
- (void)keyBoardWillShow:(NSNotification *)note
{
// 获取用户信息
NSDictionary *userInfo = [NSDictionary dictionaryWithDictionary:note.userInfo];
// 获取键盘高度
CGRect keyBoardBounds = [[userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
CGFloat keyBoardHeight = keyBoardBounds.size.height;
// 获取键盘动画时间
CGFloat animationTime = [[userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] floatValue];
}
//键盘收起
- (void)keyBoardWillShow:(NSNotification *)note{
}
