同一个 UITableViewCell 中的两个标签约束

Question

我想在每个单元格中添加两个标签，左标签作为描述，右标签是一个类别，我正在使用 SnapKit 库进行自动布局。

问题是我需要为描述设置一个不超过正确标签的约束，以防在我设置description.numberOfLines = 0 时描述很长，但它不起作用。

let descriptionLabel = UILabel()
        descriptionLabel.textColor = .black
        descriptionLabel.numberOfLines = 0

        let categoryLabel = UILabel()
        categoryLabel.textColor = .darkGray

        descriptionLabel.snp.makeConstraints {
            $0.left.equalToSuperview().offset(5)
            $0.top.equalToSuperview().offset(5)
            $0.right.equalTo(categoryLabel.snp.left).offset(-15).priority(.high)
            $0.bottom.equalToSuperview().offset(-2)
        }

        categoryLabel.snp.makeConstraints {
            $0.right.equalToSuperview().offset(-5)
            $0.top.equalToSuperview().offset(5)
        }

预期结果，描述标签不会超过正确的类别标签，但实际结果并非如此。

Answer 1

这应该可以修复您的布局。见

// 1: 2: 3: 

下面代码中的cmets：

class TestCell: UITableViewCell {
    static let identifier: String = "test_cell_identifier"

    var descriptionLabel: UILabel!
    var categoryLabel: UILabel!

    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        self.configure()
    }

    func configure() {
        descriptionLabel = UILabel()
        categoryLabel = UILabel()
        descriptionLabel.backgroundColor = .cyan
        categoryLabel.backgroundColor = .yellow

        descriptionLabel.numberOfLines = 0

        contentView.addSubview(descriptionLabel)
        contentView.addSubview(categoryLabel)

        descriptionLabel.snp.makeConstraints {
            $0.left.equalToSuperview().offset(5)
            $0.top.equalToSuperview().offset(5)
            // 1: default priority is .required
            $0.right.equalTo(self.categoryLabel.snp.left).offset(-15)
            $0.bottom.equalToSuperview().offset(-2)
        }

        categoryLabel.snp.makeConstraints {
            $0.right.equalToSuperview().offset(-5)
            $0.top.equalToSuperview().offset(5)
        }

        // 2: prevent category label from being compressed
        categoryLabel.setContentCompressionResistancePriority(.required, for: .horizontal)

        // 3: prevent category label from stretching if description label is really short
        categoryLabel.setContentHuggingPriority(.required, for: .horizontal)

    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

结果：

Answer 2

高优先级意味着当描述标签文本很长时它会被破坏

1- 成功

$0.right.equalTo(categoryLabel.snp.left).offset(-15) 

2- 将categoryLabel 的水平contentCompressionResistance 设置为1000