UITableViewCell

Question

所以我试图通过使用UIStackView来了解如何在代码中执行ui：

请注意，图像可以隐藏，甚至可以有不同的大小。关于图像唯一不变的是宽度。

以下是我提出的课程：

public class MenuItemTableViewCell: UITableViewCell {

    //MARK: UI elements
    var titleLabel = UILabel()
    var detailsLabel = UILabel()
    var itemImageView = UIImageView()
    var mainStackView = UIStackView()

    //MARK: Variables
    var menuItem: MenuItem? {
        didSet {
            if let item = menuItem {
                titleLabel.text = item.name
                detailsLabel.text = item.itemDescription
                if let imageURL = item.imageURL {
                    itemImageView.af_setImage(withURL: imageURL) { [weak self] response in

                        guard let imageView = self?.itemImageView else {
                            return
                        }

                        switch response.result {
                        case .success(let image):

                            // Instance variable:
                            var imageAspectRatioConstraint: NSLayoutConstraint?

                            // When you set the image:
                            imageAspectRatioConstraint?.isActive = false
                            imageAspectRatioConstraint = imageView.heightAnchor.constraint(
                                equalTo: imageView.widthAnchor,
                                multiplier: 100 / image.size.height)
                            imageAspectRatioConstraint!.isActive = true
                        default:
                            return
                        }
                    }
                } else {
                    itemImageView.isHidden = true
                }
            } else {
                titleLabel.text = ""
                detailsLabel.text = ""
                itemImageView.image = nil
            }
        }
    }

    override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)

        initViews()
    }

    required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }


    private func initViews() {
        self.accessoryType = .disclosureIndicator
        self.selectionStyle = .none

        setupMainStackView()
        setupTitleLabel()
        setupDetailLabel()
        setupItemImageViewLabel()
    }

    //MARK: Components setup
    private func setupMainStackView() {
        mainStackView.alignment = .fill
        mainStackView.distribution = .fillProportionally
        mainStackView.spacing = 5
        mainStackView.axis = .vertical
        mainStackView.translatesAutoresizingMaskIntoConstraints = false
        mainStackView.layoutMargins = UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)
        mainStackView.isLayoutMarginsRelativeArrangement = true
        mainStackView.setContentCompressionResistancePriority(UILayoutPriorityRequired, for: .vertical)
        mainStackView.distribution = .fillProportionally
        self.contentView.addSubview(mainStackView)

        addMainStackViewContraints()
    }

    //
    // Title Label
    //
    private func setupTitleLabel() {

        titleLabel.textColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 1)
        titleLabel.numberOfLines = 1
        mainStackView.addArrangedSubview(titleLabel)

        addTitleLabelConstraints()
    }

    //
    // Detail Label
    //
    private func setupDetailLabel() {
        detailsLabel.textColor = #colorLiteral(red: 0.501960814, green: 0.501960814, blue: 0.501960814, alpha: 1)

        detailsLabel.setContentHuggingPriority(UILayoutPriorityRequired, for: .vertical)
        detailsLabel.numberOfLines = 2
        mainStackView.addArrangedSubview(detailsLabel)

        addDetailsLabelContraints()
    }

    //
    // Item Image
    //
    private func setupItemImageViewLabel() {
        itemImageView.contentMode = .scaleAspectFit
        itemImageView.clipsToBounds = true
        mainStackView.addArrangedSubview(itemImageView)

        addItemImageViewConstraitns()
    }

    //MARK: Constraints setup
    private func addTitleLabelConstraints() {
        titleLabel.translatesAutoresizingMaskIntoConstraints = false

        titleLabel.setContentCompressionResistancePriority(UILayoutPriorityRequired, for: .vertical)
        titleLabel.setContentHuggingPriority(UILayoutPriorityRequired, for: .vertical)
    }

    func addDetailsLabelContraints() {
        detailsLabel.translatesAutoresizingMaskIntoConstraints = false

        detailsLabel.setContentCompressionResistancePriority(UILayoutPriorityRequired, for: .vertical)
        detailsLabel.setContentHuggingPriority(UILayoutPriorityRequired, for: .vertical)
    }

    func addItemImageViewConstraitns() {
        itemImageView.translatesAutoresizingMaskIntoConstraints = false
        itemImageView.widthAnchor.constraint(equalTo: mainStackView.widthAnchor).isActive = true
        itemImageView.leftAnchor.constraint(equalTo: mainStackView.leftAnchor).isActive = true
    }

    private func addMainStackViewContraints() {
        mainStackView.topAnchor.constraint(equalTo: self.contentView.topAnchor).isActive = true
        mainStackView.bottomAnchor.constraint(equalTo: self.contentView.bottomAnchor).isActive = true
        mainStackView.leftAnchor.constraint(equalTo: self.contentView.leftAnchor).isActive = true
        mainStackView.rightAnchor.constraint(equalTo: self.contentView.rightAnchor).isActive = true
    }
}

目前它看起来像这样：

如果我从我的UIStackView中删除了底部约束，那就是这样的：

有助于更好地了解UIStackView如何运作以及在UITableViewCell中自动调整大小{...}}，我们非常感谢

Answer 1

你的逻辑是什么样的：

- (CGSize) collectionView:(UICollectionView *)collectionView
                   layout:(UICollectionViewLayout*)collectionViewLayout
   sizeForItemAtIndexPath:(NSIndexPath *)indexPath

应该是......

• 抓取此索引路径的单元格
• 根据宽度确定单元格高度

• 返回适当的高度

  这里有一些很好的例子what is NSLayoutConstraint "UIView-Encapsulated-Layout-Height" and how should I go about forcing it to recalculate cleanly

Answer 2

通常，在UITableViewCell中使用UIStackView并不是一个好主意。它可能会导致性能问题。但是，如果您愿意，可以在配置时尝试调用单元格的layoutIfNeeded（）方法（特别是在设置单元格的图像视图之后）。也许它会有所帮助。