ios - UIScrollView 内容插图不适用于键盘高度

Question

我试图在键盘隐藏 UITextField 时移动 UIScrollView，方法是使用显示的 contentInsets 更改大小。

但是，它不适用于键盘高度。键盘高度为 216，但如果我将底部插图设置为 iPhone 纵向模式的 515 和 iPhone 横向模式的 310，它只会在正确的位置停止滚动。为什么这些尺寸会如此不同？我不想硬编码这些任意值。

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.view.frame = self.parentViewController.view.frame;

    [self.textView becomeFirstResponder];

    NSLog(@"scrollview: %f,%f, parent: %f,%f", self.view.frame.size.height, self.view.frame.size.width, self.parentViewController.view.frame.size.height, self.parentViewController.view.frame.size.width);

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

- (void)keyboardWasShown:(NSNotification *)notification
{
    if([[UIDevice currentDevice]userInterfaceIdiom]==UIUserInterfaceIdiomPhone) {

        // Step 1: Get the size of the keyboard.
        CGFloat keyboardHeight = [[[notification userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size.height;

        // Step 2: Adjust the bottom content inset of your scroll view by the keyboard height.
        UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, keyboardHeight, 0.0);
        ((UIScrollView*)self.view).contentInset = contentInsets;
        ((UIScrollView*)self.view).scrollIndicatorInsets = contentInsets;

        // Step 3: Scroll the target text field into view.
        CGRect aRect = self.view.frame;
        aRect.size.height = aRect.size.height - keyboardHeight;
        if (!CGRectContainsPoint(aRect, self.textView.frame.origin) ) {
            CGPoint scrollPoint = CGPointMake(0.0, self.textView.frame.origin.y - keyboardHeight);
            [((UIScrollView*)self.view) setContentOffset:scrollPoint animated:YES];
        }
    }
}

- (void) keyboardWillHide:(NSNotification *)notification {
    UIEdgeInsets contentInsets = UIEdgeInsetsZero;
    ((UIScrollView*)self.view).contentInset = contentInsets;
    ((UIScrollView*)self.view).scrollIndicatorInsets = contentInsets;
}

编辑:

在键盘打开之前，我打印出来:

NSLog(@"scrollview: %f,%f, parent: %f,%f", self.view.frame.size.height, self.view.frame.size.width, self.parentViewController.view.frame.size.height, self.parentViewController.view.frame.size.width);

它打印出这个:

scrollview: 431.000000,320.000000, parent: 431.000000,320.000000

Answer 1

我认为主要问题是您需要使用 UIKeyboardFrameEndUserInfoKey 而不是 UIKeyboardFrameBeginUserInfoKey。

话虽如此，我已经编写了此方法的不同版本，即使 ScrollView 未放置在屏幕底部也可以使用，并且可能更适合您:

请注意，我使用 self.activeTextField 而不是 self.textField。

// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
    // Calculate the frame of the scrollview, in self.view's coordinate system
    UIScrollView *scrollView    = self.scrollView;
    CGRect scrollViewRect       = [self.view convertRect:scrollView.frame fromView:scrollView.superview];

    // Calculate the frame of the keyboard, in self.view's coordinate system
    NSDictionary* info          = [aNotification userInfo];
    CGRect kbRect               = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    kbRect                      = [self.view convertRect:kbRect fromView:nil];

    // Figure out where the two frames overlap, and set the content offset of the scrollview appropriately
    CGRect hiddenScrollViewRect = CGRectIntersection(scrollViewRect, kbRect);
    if (!CGRectIsNull(hiddenScrollViewRect))
    {
        UIEdgeInsets contentInsets       = UIEdgeInsetsMake(0.0,  0.0, hiddenScrollViewRect.size.height,  0.0);
        scrollView.contentInset          = contentInsets;
        scrollView.scrollIndicatorInsets = contentInsets;
    }

    [self scrollToActiveTextField];
}

// Called when the UIKeyboardWillHideNotification is sent
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
    self.scrollView.contentInset          = UIEdgeInsetsZero;
    self.scrollView.scrollIndicatorInsets = UIEdgeInsetsZero;
}

- (void)scrollToActiveTextField
{
    if (self.activeTextField)
    {
        CGRect visibleRect = self.activeTextField.frame;
        visibleRect        = [self.scrollView convertRect:visibleRect fromView:self.activeTextField.superview];
        visibleRect        = CGRectInset(visibleRect, 0.0f, -5.0f);
        [self.scrollView scrollRectToVisible:visibleRect animated:YES];
    }
}