Swift 对于UIScrollView，以编程方式显示的UIView带有错误可滚动内容大小是不明确的。只是第一次

我在使用包含UIScrollView的UIViewController时遇到异常行为。 从另一个ViewController推送ViewController。视图的布局如下所示

• UIView
  • UIScrollView
    • UIView
      • UIImageVIew
        • UILabel
      • 乌斯塔克视图

设置约束和更新stackView内容的方法如下

private extension PresentationViewController {

    func setupView() {
        isScrolling = true

        view.addSubview(scrollView)
        scrollView.snp.makeConstraints { (builder) in
            builder.top.left.bottom.right.equalToSuperview()
        }

        scrollView.addSubview(contenView)
        contenView.snp.makeConstraints { (builder) in
            builder.top.left.bottom.right.equalToSuperview()
            builder.width.equalToSuperview()
        }

        contenView.addSubview(headerImageView)
        headerImageView.snp.makeConstraints { (builder) in
            builder.top.left.right.equalToSuperview()
            builder.height.equalTo(view.frame.height / 2)
        }

        headerImageView.addSubview(headerTitleLabel)
        headerTitleLabel.snp.makeConstraints { (builder) in
            builder.left.right.equalToSuperview()
            builder.centerX.equalToSuperview()
            builder.centerY.equalToSuperview()
        }

        contenView.addSubview(presentationStackView)
        presentationStackView.snp.makeConstraints { (builder) in
            builder.top.equalTo(headerImageView.snp.bottom).inset(-Margins.xxLarge)
            builder.left.right.equalToSuperview()
            builder.bottom.equalTo(scrollView.snp.bottom)
        }

    }

    func updateView(presentationResponse: PresentationResponse?) {
        guard let presentationResponse = presentationResponse else { return }

        let firstPresentation = presentationResponse.presentationItems[0]
        titleView.title = presentationResponse.galleryName

        headerImageView.sd_setImage(with: URL(string: firstPresentation.imageSet.fullSize ?? ""), placeholderImage: nil)
        headerTitleLabel.text = presentationResponse.galleryName

        for item in presentationResponse.presentationItems.dropFirst() {

            let sectionImageView = UIImageView()
            sectionImageView.contentMode = .scaleAspectFit
            sectionImageView.clipsToBounds = true

            let sectionCaptionLabel = BaseLabel(withConfiguration: .headline)
            sectionCaptionLabel.text = item.rowCaption

            let sectionView = UIView()
            sectionView.addSubview(sectionImageView)
            sectionView.addSubview(sectionCaptionLabel)

            sectionImageView.sd_setImage(with: URL(string: item.imageSet.defaultImage ?? "")) { [weak self, weak sectionView] (image, error, _, _) in

                guard let strongSelf = self,
                    let sectionView = sectionView,
                    let image = image else { return }

                strongSelf.presentationStackView.addArrangedSubview(sectionView)

                sectionImageView.snp.makeConstraints { (builder) in
                    builder.top.left.bottom.equalToSuperview().inset(Margins.medium)
                    let width:CGFloat = strongSelf.view.frame.size.width / 3
                    builder.width.equalTo(width)
                    builder.height.equalTo(width * (1 / image.aspectRatioValue))

                }

                sectionCaptionLabel.snp.makeConstraints { (builder) in
                    builder.left.equalTo(sectionImageView.snp.right).inset(-Margins.medium)
                    builder.top.right.equalToSuperview().inset(Margins.medium)
                }

            }

        }

    }

}

与后端的异步操作完成后，将在ViewDidLoad和updateView（：）中触发setupView（）

正如您可能已经看到的，我正在使用Snapkit进行约束。 使用调试器工具检查UI时，我收到以下消息：

Scrollable content size is ambiguous for UIScrollView

这个问题似乎与UIStackView有关，因为它没有显示出来。

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但是，如果我返回并再次按下，则不会出现错误，所有内容都会正确显示。

只需将等高和等宽约束添加到StackView视图中，相对于主视图，而不是UIScrollView。换句话说，容器视图的约束绑定到UIScrollView的superview

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在此之后，您的故事板中将不会出现警告，您可以继续为子视图添加约束。

如果布局显示正确，您就不必担心

Scrollable content size is ambiguous for UIScrollView

调试视图层次结构中出现警告。但是，如果要删除它，请在堆栈视图设置中添加一行：

    presentationStackView.snp.makeConstraints { (builder) in
        builder.top.equalTo(headerImageView.snp.bottom).inset(-Margins.xxLarge)
        builder.left.right.equalToSuperview()
        builder.bottom.equalTo(scrollView.snp.bottom)

        // add this line
        builder.height.equalTo(0).priority(250)

    }

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<>这将使堆栈视图在自动布局时空的有效高度（为零）但是

250的低优先级将允许它在添加排列的子视图时垂直扩展。
谢谢。我不使用故事板。所有UI都是通过编程实现的。你能把你的意思写下来吗？非常感谢。