当内容太多时，UILabel 在 StackView 中消失

问题描述

我有一个 UIStackView，其中包含三个子视图：标题 (UILabel)、正文 (UILabel) 和帖子图像 (UIImageView)。仅当帖子具有 imageURL 时才会添加最后一张图片（这是可选的。）

看下面，你可以看到当我显示图像时，UILabel 不知何故从 stackView 中消失了。我该如何解决这个问题？

附言展望未来，当用户从那些缺少 imageViewURL 的帖子中滚动时，我将要删除 imageViews。关于如何在此处进行的任何提示？再次感谢您。

以下是相关代码：

class FeedTableViewCell: UITableViewCell {
//MARK: Public properties
var post: Post?{
    didSet{
        guard let post = post else {return}

        // Adding user's name
        let attributedText = NSMutableAttributedString(string: post.author.name + " → " + post.group.name,attributes: [NSAttributedString.Key.font: UIFont.boldSystemFont(ofSize: 14)])

        // Adding date and user's first name
        let dateFormatter = PostDateFormatter()
        dateFormatter.dateStyle = .long
        dateFormatter.timeStyle = .short
        attributedText.append(NSAttributedString(string: "\n" + dateFormatter.string(from: post.createdAt),attributes: [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 12),NSAttributedString.Key.foregroundColor: UIColor(r: 155/255,g: 161/255,b: 171/255)]))

        // Increasing Spacing
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.linespacing = 4
        attributedText.addAttribute(NSAttributedString.Key.paragraphStyle,value: paragraphStyle,range: NSMakeRange(0,attributedText.length))

        titleLabel.attributedText = attributedText

        // Setting profile image
        iconImageView.setimage(for: post.author,setContentMode: .scaleAspectFit)

        messageTextView.text = post.content

        setupImageSubviews()
    }
}

//MARK: Private implementation
private let iconImageView = CircleImageView(size: 44)

private let titleLabel: UILabel = {
    let label = UILabel()
    label.numberOfLines = 0
    label.font = UIFont.systemFont(ofSize: 14)
    label.textColor = .black
    label.translatesAutoresizingMaskIntoConstraints = false
    return label
}()

private let messageTextView: UILabel = {
    let labelView = UILabel()
    labelView.numberOfLines = 0
    labelView.font = UIFont.systemFont(ofSize: 14)
    labelView.translatesAutoresizingMaskIntoConstraints = false
    return labelView
}()

override init(style: UITableViewCell.CellStyle,reuseIdentifier: String?) {
    super.init(style: style,reuseIdentifier: reuseIdentifier)
    setupdefaultviews()

}

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

}

var stackView = UIStackView()

func setupdefaultviews(){
    backgroundColor = UIColor.white

    stackView.addArrangedSubview(titleLabel)
    stackView.addArrangedSubview(messageTextView)

    contentView.addSubview(iconImageView)
    contentView.addSubview(stackView)

    iconImageView.anchor(top: contentView.topAnchor,leading: contentView.leadingAnchor,bottom: nil,trailing: nil,padding: .init(top: 0,left: 8,bottom: 0,right: 0),size: CGSize(width: 44,height: 44))

    stackView.anchor(top: contentView.topAnchor,leading: iconImageView.trailingAnchor,bottom: contentView.bottomAnchor,trailing: contentView.trailingAnchor,bottom: 8,right: 8))
    stackView.axis = .vertical
}

private func setupImageSubviews() {

    guard let imageURL = post?.imageURL else {return} // if no image exists,return,preventing image view from taking extra memory and performance to initialize and calculate constraints

    // initialize here instead of globally,so it doesnt take extra memory holding this when no image exists.
    let messageImageView: UIImageView = {
        let imageView = UIImageView()
        let contentimage = UIImage(systemName: "person.crop.circle.fill")!.withTintColor(.gray).withRenderingMode(.alwaysOriginal)
        imageView.kf.setimage(with: imageURL,placeholder: contentimage)
        imageView.contentMode = .scaleAspectFill
        imageView.layer.masksToBounds = true
        imageView.layer.borderWidth = 1
        imageView.translatesAutoresizingMaskIntoConstraints = false
        return imageView
    }()

    stackView.addArrangedSubview(messageImageView)
}}

解决方法

为了让人们知道我是如何解决这个问题的，我试图使用一个单元格模板来处理两种不同类型的单元格。这是一个错误，而是使用此 link Using Auto Layout in UITableView for dynamic cell layouts & variable row heights 中的信息正确创建两个单元格模板。我还发现此代码可确保单元格正确显示标题：

    // Keeps the title text always showing
override func didMoveToSuperview() {
    super.didMoveToSuperview()
    layoutIfNeeded()
}