关闭和打开键盘的通知

在ViewController.m中添加代码：

-(void)viewWillAppear:(BOOL)animated
{
    // 注册键盘出现通知
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];
    // 注册键盘隐藏通知
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidHide:) name:UIKeyboardDidHideNotification object:nil];
    [super viewWillAppear:animated];
}

-(void)viewWillDisappear:(BOOL)animated
{
    // 解除键盘出现通知
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidShowNotification object:nil];
    // 解除键盘隐藏通知
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidHideNotification object:nil];
    [super viewWillDisappear:animated];
}

-(void)keyboardDidShow: (NSNotification *)notif {
    NSLog(@"键盘打开");
}

-(void)keyboardDidHide: (NSNotification *)notif {
    NSLog(@"键盘关闭”);