代碼如下：

- (void)viewDidLoad
{
    [super viewDidLoad];

    //增加監(jiān)聽，當(dāng)鍵盤出現(xiàn)或改變時(shí)收出消息
    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillShow:)
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    //增加監(jiān)聽，當(dāng)鍵退出時(shí)收出消息
    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillHide:)
                                             name:UIKeyboardWillHideNotification
                                           object:nil];    
}

 //當(dāng)鍵盤出現(xiàn)或改變時(shí)調(diào)用
- (void)keyboardWillShow:(NSNotification *)aNotification
{
    //獲取鍵盤的高度
    NSDictionary *userInfo = [aNotification userInfo];
    NSValue *aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
    CGRect keyboardRect = [aValue CGRectValue];
   int height = keyboardRect.size.height;
}

//當(dāng)鍵退出時(shí)調(diào)用
- (void)keyboardWillHide:(NSNotification *)aNotification{}