单行文本在UILabel中需要两行 [英] Single line text takes two lines in UILabel

问题描述

如您在图片中看到的，中间单元格有一个UILabel，它消耗两行，但是文本实际上是一行.看来，如果文本只需要几个字符即可创建新行，则iOS会假定它已经有2行.这很奇怪.

As you can see in the picture the middle cell has a UILabel that consumes two lines, but the text is actually a single line. It seems that if the text needs only few characters to create a new line, iOS assumes that it already has 2 lines. This is odd.

这是我创建标签的方式:

This is how I create the label:

self.titleLabel.lineBreakMode = .ByTruncatingTail
self.titleLabel.numberOfLines = 0
self.titleLabel.textAlignment = .Left

约束设置一次:

self.titleLabel.autoPinEdgeToSuperviewEdge(.Top)
self.titleLabel.autoPinEdgeToSuperviewEdge(.Leading)
self.titleLabel.autoPinEdgeToSuperviewEdge(.Trailing)
self.titleLabel.autoPinEdgeToSuperviewEdge(.Bottom)

奇怪的是，当滚动表以使奇数单元格消失并再次向后滚动时，它具有其正常高度.滚动后:

The weird thing is, when the table is scrolled so that the odd cell disappears and scrolled back again it has its normal height. After scroll:

任何想法有什么问题吗?我正在使用swift，xcode6.1和iOS8.1

Any ideas whats wrong? I am using swift, xcode6.1 and iOS8.1

TableViewController:

TableViewController:

override func viewDidLoad() {
    super.viewDidLoad()

    self.tableView.registerClass(CityTableViewCell.self, forCellReuseIdentifier:"cell")
    self.tableView.rowHeight = UITableViewAutomaticDimension
    self.tableView.estimatedRowHeight = 52
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    if let cell: CityTableViewCell = tableView.dequeueReusableCellWithIdentifier("cell") as? CityTableViewCell {
        // Configure the cell for this indexPath
        cell.updateFonts()
        cell.accessoryType = UITableViewCellAccessoryType.DisclosureIndicator
        if indexPath.row == 1 {
            cell.titleLabel.text = "Welcome to city 17, Mr. Gordon F."
        } else {
            cell.titleLabel.text = "Lamar!!!"
        }
        // Make sure the constraints have been added to this cell, since it may have just been created from scratch
        cell.setNeedsUpdateConstraints()
        cell.updateConstraintsIfNeeded()

        return cell
    }
    return UITableViewCell();
}

推荐答案

我认为您遇到了此错误: http://openradar.appspot.com/17799811 .标签未正确设置 preferredMaxLayoutWidth .

I think you met this bug: http://openradar.appspot.com/17799811. The label does not set the preferredMaxLayoutWidth correctly.

我选择的解决方法是用以下类将 UITableViewCell 子类化:

The workaround I chose was to subclass UITableViewCell with the following class:

class VFTableViewCell : UITableViewCell {

    @IBOutlet weak var testoLbl: UILabel!

    //MARK: codice temporaneo per bug http://openradar.appspot.com/17799811

    func maxWidth() -> CGFloat {

        var appMax = CGRectGetWidth(UIApplication.sharedApplication().keyWindow.frame)

        appMax -= 12 + 12    // borders, this is up to you (and should not be hardcoded here)

        return appMax
    }

    override func awakeFromNib() {
        super.awakeFromNib()

        // MARK: Required for self-sizing cells.
        self.testoLbl.preferredMaxLayoutWidth = maxWidth()
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        // MARK: Required for self-sizing cells
        self.testoLbl.preferredMaxLayoutWidth = maxWidth()
    }
}

---

OP-Note:

---

OP-Note:

似乎自动布局无法正确计算UILabel布局的宽度.在我的UITableViewCell子类中将首选宽度设置为父级宽度可以解决我的问题:

It seems that auto layout does not calculate the width of the UILabel layout correctly. Setting the preferred width to the parents width in my UITableViewCell subclass solves my problem:

self.titleLabel.preferredMaxLayoutWidth = self.frame.width

在SO上找到: https://stackoverflow.com/a/19777242/401025

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