视图高度的模糊布局

Question

我有一个UITableView，其中包含一个单元格：

Title label + UIStackView 带有一些按钮，在其下方是 UIStackView，带有另一个标签（描述）、UICollectionView（一组图像）和一个按钮。标题标签固定到前导、尾随和顶部超级视图，底部固定到UIStackView（固定到前导、尾随、标签底部和超级视图底部）。

我也在使用UITableViewAutomaticDimension，这是因为UIStackView（图像、文本）内部的内容高度可能不同。

在我将UICollectionView 添加到UIStackView 之前，一切正常，但在某些情况下添加它后布局会中断（UIStackView 中的所有内容都重叠）并且在 View UI Hierarchy 中我可以看到警告：

*UIView:0x1038635e0- AMBIGUOUS LAYOUT for UIView:0x1038635e0.Height{id: 3153}

Legend:
    * - is laid out with auto layout
    + - is laid out manually, but is represented in the layout engine because translatesAutoresizingMaskIntoConstraints = YES
    • - layout engine host
2018-01-03 10:19:58.527094+0100 Crowd Knowledge[1462:1408352] [LayoutConstraints] View has an ambiguous layout. See "Auto Layout Guide: Ambiguous Layouts" for help debugging. Displaying synopsis from invoking -[UIView _autolayoutTrace] to provide additional detail.

*Crowd_Knowledge.AttachmentsCollectionView:0x104072e00- AMBIGUOUS LAYOUT for Crowd_Knowledge.AttachmentsCollectionView:0x104072e00.minY{id: 3263}, Crowd_Knowledge.AttachmentsCollectionView:0x104072e00.Height{id: 3252}

Legend:
    * - is laid out with auto layout
    + - is laid out manually, but is represented in the layout engine because translatesAutoresizingMaskIntoConstraints = YES
    • - layout engine host
2018-01-03 10:19:58.531696+0100 Crowd Knowledge[1462:1408352] [LayoutConstraints] View has an ambiguous layout. See "Auto Layout Guide: Ambiguous Layouts" for help debugging. Displaying synopsis from invoking -[UIView _autolayoutTrace] to provide additional detail.

*UIButton:0x103854dc0'Edit solution'- AMBIGUOUS LAYOUT for UIButton:0x103854dc0'Edit solution'.minY{id: 3261}, UIButton:0x103854dc0'Edit solution'.Height{id: 3258}

Legend:
    * - is laid out with auto layout
    + - is laid out manually, but is represented in the layout engine because translatesAutoresizingMaskIntoConstraints = YES
    • - layout engine host
2018-01-03 10:19:59.247887+0100 Crowd Knowledge[1462:1408352] [LayoutConstraints] Window has a view with an ambiguous layout. See "Auto Layout Guide: Ambiguous Layouts" for help debugging. Displaying synopsis from invoking -[UIView _autolayoutTrace] to provide additional detail.

*UIView:0x1038635e0- AMBIGUOUS LAYOUT for UIView:0x1038635e0.Height{id: 3153}

Legend:
    * - is laid out with auto layout
    + - is laid out manually, but is represented in the layout engine because translatesAutoresizingMaskIntoConstraints = YES
    • - layout engine host

另外，我的UICollectionView 有一个布局，它根据内容设置高度：

class DynamicCollectionView: UICollectionView {

    override func layoutSubviews() {
        super.layoutSubviews()
        if !__CGSizeEqualToSize(bounds.size, self.intrinsicContentSize) {
            self.invalidateIntrinsicContentSize()
        }
    }

    override var intrinsicContentSize: CGSize {
        return contentSize
    }

}

我在情节提要中没有任何警告，它在 90% 的时间里都有效。如果它坏了，我所要做的就是滚动另一个单元格，这样它就会刷新并且约束再次起作用。我尝试了各种技巧来强制更新 UI (tableView.beginUpdates() + tableView.endUpdates())，但我仍然找不到始终有效的解决方案。

我正在为这个问题寻找一个干净的解决方案。

Answer 1

“UIStackView（固定在父视图的前导、尾随和底部）”

为什么它没有固定在超级视图的顶部？您还必须将其固定到超级视图的顶部。不需要固定大小...

为了一个很好的演示。见this moment of this WWDC video。我强烈建议您观看整个视频。但从那一刻开始，您将了解很多有关您的问题的信息。