ios - uikeyboardwillhidenotification 滚动时调用方法两次

Question

我有一个带有 UIScrollView 的 View 并且有很多 UITextField 我在触摸 View 后关闭键盘并且它工作正常同时我想在滚动时关闭键盘风景。我的问题是当我 ScrollView 时它正在关闭键盘但它调用方法 (keyboardWillHide) 两次，这对我设置屏幕错误造成了问题。如何防止调用该方法两次？

我的代码:

- (void)viewDidLoad {
   [super viewDidLoad];

  UITapGestureRecognizer* tapGesture = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(closeTextInput)];
tapGesture.cancelsTouchesInView = NO;
  [self.view addGestureRecognizer:tapGesture];

  _scrllView.keyboardDismissMode = UIScrollViewKeyboardDismissModeOnDrag;
}

- (void)viewWillAppear:(BOOL)animated
{
  [super viewWillAppear:animated];

  [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillHide)
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}

- (void)viewWillDisappear:(BOOL)animated
{
  [super viewWillDisappear:animated];

  [[NSNotificationCenter defaultCenter] removeObserver:self
                                                name:UIKeyboardWillShowNotification
                                              object:nil];

  [[NSNotificationCenter defaultCenter] removeObserver:self
                                                name:UIKeyboardWillHideNotification
                                              object:nil];
}

-(void)keyboardWillHide {

    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)setViewMovedUp:(BOOL)movedUp{

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3];

    CGRect rect = self.view.frame;
    if (movedUp)
    {
        if (self.view.frame.origin.y != -kOFFSET_FOR_KEYBOARD){

        rect.origin.y -= kOFFSET_FOR_KEYBOARD;
        rect.size.height += kOFFSET_FOR_KEYBOARD;
      }
  }
  else
  {
        rect.origin.y += kOFFSET_FOR_KEYBOARD;
        rect.size.height -= kOFFSET_FOR_KEYBOARD;
  }
        self.view.frame = rect;
        [UIView commitAnimations];
}

Answer 1

尝试保留一个 BOOL keyboardIsUp，如果键盘弹起则为真，然后在输入函数 keyboardWillHide 时询问 keyboardIsUp 是否为真。如果是真的，继续。如果为假，则退出函数:

-(void)keyboardWillHide 
{
    if (keyboardIsUp == NO)
        return;
    else
        //your code   

您的函数仍将被调用两次或更多次，但只会执行一次其功能。只需确保在适当的时候将 keyboardIsUp 设置为 YES 和 NO。