Swift iOS - setContentHuggingPriority 优先处理错误的标签

Question

我有一个带有 4 个标签的单元格：

2 个独立的静态标签和 2 个独立的动态标签。 2 个静态标签中的文本总是显示 Receipt #，另一个显示 Receipt Date。

我设置它的方式是静态标签都将前导锚点固定到单元格的 contentView 的 leadingAnchor。他们都将 setContentHuggingPriority 设置为 High 并将 setContentCompressionResistancePriority 设置为 Low。他们的 bottomAnchors 附加到每个匹配的动态标签的 lastBaseLineAnchor

动态标签都将其尾随锚点固定到 contentView 的尾随锚点。

receiptNumberLabel 的 leadingAnchor 固定到 receiptDateLabel 的 leadingAnchor。

receiptDateLabel 的 leadingAnchor 固定在距 staticReceiptDateLabel 10 点的位置。这个标签是应该灵活的标签，但事实并非如此。由于 receiptNumberLabels 的 leadingAnchor 遵循它，因此它也未对齐。

如您所见，staticReceiptDateLabel 更长，但它应该更短，而 receiptDateLabel 应该更长。我已经为 setContentHuggingPriority 和 setContentCompressionResistancePriority 的值尝试了不同的组合，但无论我不断得到这些结果，我该如何解决这个问题？

contentView.addSubview(receiptNumberLabel) // dynamic
contentView.addSubview(staticReceiptNumberLabel)
contentView.addSubview(receiptDateLabel) // dynamic
contentView.addSubview(staticReceiptDateLabel)

receiptNumberLabel.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 10).isActive = true
receiptNumberLabel.leadingAnchor.constraint(equalTo: receiptDateLabel.leadingAnchor, constant: 0).isActive = true
receiptNumberLabel.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -10).isActive = true
receiptNumberLabel.setContentHuggingPriority(.defaultLow, for: .horizontal)
receiptNumberLabel.setContentCompressionResistancePriority(.defaultHigh, for: .horizontal)

staticReceiptNumberLabel.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 10).isActive = true
staticReceiptNumberLabel.lastBaselineAnchor.constraint(equalTo: receiptNumberLabel.lastBaselineAnchor).isActive = true
staticReceiptNumberLabel.setContentHuggingPriority(.defaultHigh, for: .horizontal)
staticReceiptNumberLabel.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)

receiptDateLabel.topAnchor.constraint(equalTo: receiptNumberLabel.bottomAnchor, constant: 10).isActive = true
receiptDateLabel.leadingAnchor.constraint(equalTo: staticReceiptDateLabel.trailingAnchor, constant: 10).isActive = true
receiptDateLabel.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -10).isActive = true
receiptDateLabel.setContentHuggingPriority(UILayoutPriority.defaultLow, for: .horizontal)
receiptDateLabel.setContentCompressionResistancePriority(.defaultHigh, for: .horizontal)

staticReceiptDateLabel.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 10).isActive = true
staticReceiptDateLabel.lastBaselineAnchor.constraint(equalTo: receiptDateLabel.lastBaselineAnchor).isActive = true
staticReceiptDateLabel.setContentHuggingPriority(UILayoutPriority.defaultHigh, for: .horizontal)
staticReceiptDateLabel.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)

更新

在评论中@bsod 建议根本不要使用 hugging/compression。我最初没有使用它们并且出现了同样的问题，我转而使用它们作为最后的手段。这是没有 hugging/compression.

的代码

receiptNumberLabel.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 10).isActive = true
receiptNumberLabel.leadingAnchor.constraint(equalTo: receiptDateLabel.leadingAnchor, constant: 0).isActive = true
receiptNumberLabel.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -10).isActive = true

staticReceiptNumberLabel.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 10).isActive = true
staticReceiptNumberLabel.lastBaselineAnchor.constraint(equalTo: receiptNumberLabel.lastBaselineAnchor).isActive = true

receiptDateLabel.topAnchor.constraint(equalTo: receiptNumberLabel.bottomAnchor, constant: 10).isActive = true
receiptDateLabel.leadingAnchor.constraint(equalTo: staticReceiptDateLabel.trailingAnchor, constant: 10).isActive = true
receiptDateLabel.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -10).isActive = true

staticReceiptDateLabel.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 10).isActive = true
staticReceiptDateLabel.lastBaselineAnchor.constraint(equalTo: receiptDateLabel.lastBaselineAnchor).isActive = true

Answer 1

忘记 hugging/compression API 并以此为起点。从 upper-left 标签开始，一直向下 left-to-right、top-to-bottom。请注意，静态日期标签的顶部锚点固定在收据编号值标签的底部，以防它有多行。

staticReceiptNumberLabel.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 10).isActive = true
staticReceiptNumberLabel.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 10).isActive = true

receiptNumberLabel.topAnchor.constraint(equalTo: staticReceiptNumberLabel.topAnchor).isActive = true
receiptNumberLabel.leadingAnchor.constraint(equalTo: staticReceiptNumberLabel.trailing, constant: 10).isActive = true
receiptNumberLabel.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -10).isActive = true

staticReceiptDateLabel.leadingAnchor.constraint(equalTo: staticReceiptNumberLabel.leadingAnchor).isActive = true
staticReceiptDateLabel.topAnchor.constraint(equalTo: receiptNumberLabel.bottomAnchor).isActive = true

receiptDateLabel.topAnchor.constraint(equalTo: staticReceiptDateLabel.topAnchor).isActive = true
receiptDateLabel.leadingAnchor.constraint(equalTo: staticReceiptDateLabel.trailingAnchor, constant: 10).isActive = true
receiptDateLabel.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -10).isActive = true
receiptDateLabel.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -10).isActive = true

您可能还需要将标题标签的 numberOfLines 显式设置为 1，否则 UIKit 可能会截断值标签，即使其 numberOfLines 为 0。

如果出于某种原因，您甚至不想扩大静态标签的大小，也许是因为您给它们设置了背景色，那么您可以引入 hugging/compression API。如果是这样，静态标签将是：

theStaticLabel.setContentCompressionResistancePriority(.defaultHigh, for: .horizontal)
theStaticLabel.setContentHuggingPriority(.defaultHigh, for: .horizontal)

动态标签为：

theDynamicLabel.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
theDynamicLabel.setContentHuggingPriority(.defaultLow, for: .horizontal)

Swift iOS - setContentHuggingPriority 优先处理错误的标签

Swift iOS - setContentHuggingPriority is prioritizing the wrong label

constraints

uilabel

ios

swift