iOS 键盘弹出时获取键盘的高度

1、在viewDidLoad方法中加入监测键盘的通知。

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHidden:) name:UIKeyboardWillHideNotification object:nil];
}

2、移除通知

-(void)dealloc
{
    //第一种方法.这里可以移除该控制器下的所有通知
    //移除当前所有通知
    NSLog(@"移除了所有的通知");
    [[NSNotificationCenter defaultCenter] removeObserver:self];

    //第二种方法.这里可以移除该控制器下名称为tongzhi的通知
    //移除名称为tongzhi的那个通知
    NSLog(@"移除了名称为tongzhi的通知");
    [[NSNotificationCenter defaultCenter] removeObserver:self name:@"tongzhi" object:nil];
}

3、实现通知的方法

/**
 *  键盘将要显示
 *
 *  @param notification 通知
 */
-(void)keyboardWillShow:(NSNotification *)notification
{
//这样就拿到了键盘的位置大小信息frame，然后根据frame进行高度处理之类的信息
    CGRect frame = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    
    CGFloat endHeight = self.showScrollView.contentSize.height + frame.size.height;
    self.showScrollView.contentSize = CGSizeMake(SCREEN_WIDTH, endHeight);
    self.showScrollView.contentOffset = CGPointMake(0, self.bottomView.originY);
}

/**
 *  键盘将要隐藏
 *
 *  @param notification 通知
 */
-(void)keyboardWillHidden:(NSNotification *)notification
{
    CGRect frame = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    
    CGFloat endHeight = self.showScrollView.contentSize.height - frame.size.height;
    self.showScrollView.contentSize = CGSizeMake(SCREEN_WIDTH, endHeight);
}