Question

目的：

使用自动布局和UITableView在UITableViewAutomaticDimension的自定义单元格上显示多行标签。
单元格应根据每个UILabel中的文字而有所不同。

我做了什么：

二手自动布局
tableView.rowHeight = UITableViewAutomaticDimension
tableView.estimatedRowHeight = 100
label.numberOfLines = 0（标签是我创建的新标签）
label.setTranslatesAutoresizingMaskIntoConstraints(false)
将UILabel添加到contentView
从UILabel添加约束到内容视图

问题：

当我使用自定义单元格
有时滚动不是很顺利

与UITableViewCell尝试相同：

tableView.rowHeight = UITableViewAutomaticDimension
tableView.estimatedRowHeight = 100
textLabel.numberOfLines = 0（textLabel）

UITableViewCell

滚动似乎很顺利
无剪辑，文字显示正确
打印cell.textLabel?.preferredMaxLayoutWidth，显示0

问题：

为什么UITableViewCell而不是我的自定义单元格能正常工作？
在这两种情况下都没有设置preferredMaxLayoutWidth。
请告诉我我错过的内容。

自定义单元格的代码：

    class MultilineLabelCell : UITableViewCell {

    let label = UILabel()

    //MARK: Initializers

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

        setup()
    }

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        setup()
    }

    //MARK: Setup Views

    func setup() {
        setupLabel()
        setupLayout()
    }

    func setupLabel() {

        label.setTranslatesAutoresizingMaskIntoConstraints(false)

        label.numberOfLines = 0

        contentView.addSubview(label)
    }

    func setupLayout() {

        let views = ["label" : label]

        let horizontalConstraints = NSLayoutConstraint.constraintsWithVisualFormat("H:|-[label]-|",
            options: .allZeros,
            metrics: nil,
            views: views)

        let verticalConstraints = NSLayoutConstraint.constraintsWithVisualFormat("V:|-[label]-|",
            options: .allZeros,
            metrics: nil,
            views: views)

        contentView.addConstraints(horizontalConstraints)
        contentView.addConstraints(verticalConstraints)
    }
}

查看控制器代码

override func loadView() {
    super.loadView()

    tableView.registerClass(MultilineLabelCell.self, forCellReuseIdentifier: ViewController.cellIdentifier)

    tableView.rowHeight = UITableViewAutomaticDimension
    tableView.estimatedRowHeight = 100

}
    func populateData() {

        dataArray.append("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat")

        dataArray.append("Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum")


        dataArray.append("Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam,")

        dataArray.append("nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?")

        dataArray.append("But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer of the truth, the master-builder of human happiness. No one rejects, dislikes, or avoids pleasure itself, because it is pleasure, but because those who do not know how to pursue pleasure rationally encounter consequences that are extremely painful. Nor again is there anyone who loves or pursues or desires to obtain pain of itself, because it is pain, but because occasionally circumstances occur in which toil and pain can procure him some great pleasure. To take a trivial example, which of us ever undertakes laborious physical exercise, except to obtain some advantage from it? But who has any right to find fault with a man who chooses to enjoy a pleasure that has no annoying consequences, or one who avoids a pain that produces no resultant pleasure?")
    }

    override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCellWithIdentifier(ViewController.cellIdentifier) as! MultilineLabelCell

        cell.label.numberOfLines = 0
        cell.label.text = dataArray[indexPath.row]

        return cell
    }

enter image description here

Answer 1

虽然在UITableViewCell的内容视图中以编程方式提供约束视图/控件，并希望根据文本长度获得动态单元格大小，但您需要明确地给出所有四个边的填充（提供一些值）。按以下方式进行更改。看起来像一个bug

在setupLayout方法

中

func setupLayout() {

        let views = ["label" : label]

        let horizontalConstraints = NSLayoutConstraint.constraintsWithVisualFormat("H:|-5-[label]-5-|",
            options: .allZeros,
            metrics: nil,
            views: views)

        let verticalConstraints = NSLayoutConstraint.constraintsWithVisualFormat("V:|-5-[label]-5-|",
            options: .allZeros,
            metrics: nil,
            views: views)

        contentView.addConstraints(horizontalConstraints)
        contentView.addConstraints(verticalConstraints)
    }

自定义单元格，使用UITableViewAutomaticDimension显示多行标签

1 个答案: