iOS 在视图更改时关闭键盘

Question

我有一个基于视图的应用程序，在其中一个子视图中有一个 UIScrollView。我编写了处理程序来在键盘出现和消失时调整滚动视图的大小。我希望在用户离开视图时关闭键盘，因此我在 viewWillDisappear 中调用 [currentField resignFirstResponder]。这会关闭键盘，但不会调用处理程序来调整滚动视图的大小（当我在其他地方调用相同的代码时，它会这样做）。有什么建议吗？

编辑：这些是我使用的处理程序：

-(void) keyboardWasShown:(NSNotification*) notification
{
    if(keyboardShown)
        return;

    NSDictionary* info=[notification userInfo];
    NSValue* value=[info objectForKey:UIKeyboardFrameEndUserInfoKey];
    CGSize keyboardSize=[value CGRectValue].size;
    CGRect viewFrame=[scrollView frame];
    viewFrame.size.height-=keyboardSize.height;
    scrollView.frame=viewFrame;

    keyboardShown=YES;
}

-(void) keyboardWasHidden:(NSNotification*) notification
{
    NSDictionary* info=[notification userInfo];
    NSValue* value=[info objectForKey:UIKeyboardFrameEndUserInfoKey];
    CGSize keyboardSize=[value CGRectValue].size;
    CGRect viewFrame=[scrollView frame];
    viewFrame.size.height+=keyboardSize.height;
    scrollView.frame=viewFrame;

    keyboardShown=NO;
}

当我在其他地方调用 [currentField resignFirstResponder] 时，它会毫无问题地调用处理程序。

Answer 1

因此，在发布 UIKeyboardDidHideNotification 之前，您已被删除为观察者，很高兴我能提供帮助。但是观察 UIKeyboardWillHideNotification 和 UIKeyboardWillShowNotification 可能足以了解您对键盘的反应。键盘通知有一个用户信息键 UIKeyboardAnimationDurationUserInfoKey，您可以使用它通过键盘动画对帧调整进行动画处理。如果您不将视图设置为新位置，这可以避免您的视图产生“沉闷”的感觉。以下是您可以执行的操作的简单示例：

-(void)keyboardWillNotificationTarget:(NSNotification *)note{
        // Find current keyboard origin Y 
    NSValue *keyboardCurrentFrameValue = [note.userInfo objectForKey:UIKeyboardFrameBeginUserInfoKey];
    CGFloat currentOriginY = keyboardCurrentFrameValue.CGRectValue.origin.y;
        // Find keyboard Y that will be
    NSValue *keyboardNewFrameValue = [note.userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
    CGFloat newOriginY = keyboardNewFrameValue.CGRectValue.origin.y;
        // Calculate new frame for scrollView
    CGFloat heightChangeForScrollView = newOriginY - currentOriginY;
    CGRect svFrame = scrollView.frame;
    svFrame.size.height += heightChangeForScrollView;
        // Find duration of animation
    NSNumber *animationDurationNumber = [note.userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
    CGFloat animationDuration = animationDurationNumber.floatValue;
        // Animate scrollView with keyboard
    [UIView animateWithDuration:animationDuration animations:^{
        scrollView.frame = svFrame;
    }];
}

现在您只需添加此方法作为两个通知的目标：

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