以编程方式使用错误的可滚动内容大小的 UIView 对于 UIScrollView 是不明确的。只是第一次

Question

我的 UIViewController 包含一个 UIScrollView，我遇到了一个奇怪的行为。 ViewController 是从另一个 ViewController 推送的。视图布局如下

UI查看
- UI滚动视图
  - UI查看
    - UIImageVIew
      - UI标签
    - UIStackView

我设置约束和更新 stackView 内容的方式如下。

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)
                }

            }

        }

    }

}

当对后端的异步操作完成时，在 ViewDidLoad 和 updateView(:) 中触发 setupView()。

如您所见，我正在使用 Snapkit 作为我的约束。使用调试器工具检查我的 UI 时，我收到消息：

Scrollable content size is ambiguous for UIScrollView

问题似乎与 UIStackView 有关，因为它没有显示。但是，如果我返回并再次按下，我就没有错误，并且一切都正确显示。

Answer 1

只需将 Equal Height 和 Equal Width 约束添加到与主视图相关的 StackView 视图，而不是 UIScrollView。换句话说，容器视图的约束与 UIScrollView 的超级视图相关联。

之后你的 Storyboard 中将不会有警告，你可以继续为你的子视图添加约束。

Answer 2

如果布局显示正确，您真的不需要担心

Scrollable content size is ambiguous for UIScrollView

调试视图层次结构中出现警告。但是，如果您想摆脱它，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)

    }

这将为堆栈视图提供一个有效高度（零），以便自动布局在它为空时考虑...但是 250 的低优先级将允许它在您添加时垂直扩展排列的子视图。

以编程方式使用错误的可滚动内容大小的 UIView 对于 UIScrollView 是不明确的。只是第一次

Programmatically UIView with error Scrollable content size is ambiguous for UIScrollView. Only the first time

uiscrollview

uikit

swift

uistackview

snapkit