在垂直堆栈视图中设置图像子视图的高度

Question

我有一个UITableViewCell，它以堆叠模式包含内容。

1. 页眉 ( UILabel (
2. 子标题 ( UILabel (
3. 图片 ( UIImageView (
4. 内容正文 ( UILabel (

图像不是固定高度，我从远程资源下载，但是，我在渲染cell之前就知道高度，因为它包含在初始 API 响应中。

我正在尝试根据我在模型上持有的值设置此图像的高度，但是，我一直遇到autolayout问题：

(
    "<NSLayoutConstraint:0x283c90d20 V:|-(8)-[UIStackView:0x1050072a0]   (active, names: '|':UITableViewCellContentView:0x105007ad0 )>",
    "<NSLayoutConstraint:0x283c90e10 UIStackView:0x1050072a0.bottom == UITableViewCellContentView:0x105007ad0.bottom - 8   (active)>",
    "<NSLayoutConstraint:0x283c90eb0 UIImageView:0x1050074a0.height == 220.073   (active)>",
    "<NSLayoutConstraint:0x283cb9720 'UISV-canvas-connection' UIStackView:0x1050072a0.top == UILabel:0x1050034a0'Hey you, get off my cloud'.top   (active)>",
    "<NSLayoutConstraint:0x283cb8910 'UISV-canvas-connection' V:[UIImageView:0x1050074a0]-(0)-|   (active, names: '|':UIStackView:0x1050072a0 )>",
    "<NSLayoutConstraint:0x283cb8190 'UISV-spacing' V:[UILabel:0x1050034a0'Hey you, get off my cloud']-(0)-[UILabel:0x105003790'You don't know me and you...']   (active)>",
    "<NSLayoutConstraint:0x283cb81e0 'UISV-spacing' V:[UILabel:0x105003790'You don't know me and you...']-(0)-[UIImageView:0x1050074a0]   (active)>",
    "<NSLayoutConstraint:0x283cba850 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x105007ad0.height == 16   (active)>"
)
Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x283c90eb0 UIImageView:0x1050074a0.height == 220.073   (active)>

我

以编程方式列出我的观点，如下所示：

class ArticleBodyCell: UITableViewCell {
    private var articleImageViewHeight: NSLayoutConstraint!
    private let contentStackView = UIStackView(frame: .zero)
    private lazy var articleHeader = UILabel(
        font: theme.font(.header),
        textColor: theme.color(.text),
        numberOfLines: 0
    )
    private lazy var articleSummary = UILabel(
        font: theme.font(.headerSmall),
        textColor: theme.color(.text),
        numberOfLines: 0
    )
    private let articleImageView = UIImageView(frame: .zero)
    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        anchorSubViews()
    }
    required init?(coder aDecoder: NSCoder) {
        return nil
    }
    func render(model: ContentArticle?) {
        guard let model = model else { return }
        articleHeader.text = model.title
        articleSummary.text = model.description
        if let asset = model.assets.first, let storageUri = asset?.storageUri {
            articleImageViewHeight.constant = model.heightForArticle
            print("do something w/",storageUri)
        }
    }
    func anchorSubViews() {
        contentView.addSubview(contentStackView)
        contentStackView.translatesAutoresizingMaskIntoConstraints = false
        articleImageViewHeight = articleImageView.heightAnchor.constraint(equalToConstant: 0)
        articleImageViewHeight.isActive = true
        NSLayoutConstraint.activate([
            contentStackView.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 8),
            contentStackView.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 8),
            contentStackView.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -8),
            contentStackView.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -8)
        ])
        contentStackView.axis = .vertical
        contentStackView.distribution = .fill
        [articleHeader, articleSummary, articleImageView].forEach { contentStackView.addArrangedSubview($0) }
    }
}

我想也许通过捕获articleImageViewHeight我可以在处理单元格渲染模型时设置高度，但这似乎不起作用。

编辑我还尝试使用以下方法调整锚点的priority，但这没有效果。

contentStackViewBottomAnchor = contentView.bottomAnchor.constraint(equalTo: contentStackView.bottomAnchor)
contentStackViewBottomAnchor.priority = .init(999)
contentStackViewBottomAnchor.isActive = true

Answer 1

设置articleImageViewHeight的优先级。

我不相信把它放在contentView上会产生任何影响。

articleImageViewHeight = articleImageView.heightAnchor.constraint(equalToConstant: 0)
articleImageViewHeight.priority = .init(999)
articleImageViewHeight.isActive = true