带有 ScrollView 和键盘的 iOS AutoLayout

Question

我的 Storyboard上有一个 View 显示用户登录表单，所以它看起来像这样:主视图-> ScrollView ->内容 View ->两个文本字段和登录按钮在顶部，一个注册按钮在 View 的底部。我使用自动布局，底部按钮有底部空间限制。当我点击文本字段并出现键盘时，我想 ScrollView 以将大小更改为可见矩形，但内容大小应保持向下滚动到注册按钮，但当 ScrollView 的大小发生变化时按钮向上移动。我怎么能做我想做的事？

我在出现键盘时使用此代码:

- (void)keyboardWillShow:(NSNotification *)aNotification
{
    NSDictionary *info = [aNotification userInfo];
    NSValue *kbFrame = [info objectForKey:UIKeyboardFrameEndUserInfoKey];
    NSTimeInterval animationDuration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    CGRect keyboardFrame = [kbFrame CGRectValue];

    CGSize s = self.scrollView.contentSize;
    CGFloat height = keyboardFrame.size.height;
    self.scrollViewBottomLayoutConstraint.constant = height;

    [UIView animateWithDuration:animationDuration animations:^{
        [self.view layoutIfNeeded];
        [self.scrollView setContentSize:s];
    }];
}

Answer 1

尝试不考虑内容大小，而是调整 ScrollView 的 contentInset 属性。这样您就不必搞乱约束。

- (void)keyboardUp:(NSNotification *)notification
{
    NSDictionary *info = [notification userInfo];
    CGRect keyboardRect = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    keyboardRect = [self.view convertRect:keyboardRect fromView:nil];

    UIEdgeInsets contentInset = self.scrollView.contentInset;
    contentInset.bottom = keyboardRect.size.height;
    self.scrollView.contentInset = contentInset;
}