Number of rows in UILabel per cell to display size

Here's a simple example that counts the number of lines in text.

The method goes recursively to find the index of the glyph, and get the chunk of the string and compare if the character in the index is the last one.

class TableViewCell: UITableViewCell {

    var index: Int = 0

    var titleLabel: UILabel!
    var numberOfLinesLabel: UILabel!

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

        titleLabel = UILabel(frame: CGRectZero)
        titleLabel.translatesAutoresizingMaskIntoConstraints = false
        titleLabel.numberOfLines = 0
        titleLabel.lineBreakMode = NSLineBreakMode.ByWordWrapping
        contentView.addSubview(titleLabel)

        numberOfLinesLabel = UILabel(frame: CGRectZero)
        numberOfLinesLabel.translatesAutoresizingMaskIntoConstraints = false
        contentView.addSubview(numberOfLinesLabel)

        contentView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-10-[titleLabel]-10-|", options: NSLayoutFormatOptions(rawValue: 0), metrics: nil, views: ["titleLabel": titleLabel]))
        contentView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-20-[titleLabel]-[numberOfLinesLabel(==28)]|", options: NSLayoutFormatOptions.AlignAllTop, metrics: nil, views: ["titleLabel": titleLabel, "numberOfLinesLabel": numberOfLinesLabel]))

    }

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

    var textDetail: String?  {
        didSet {
            titleLabel.text = textDetail
        }
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        calculateNumberOfLines()

    }

    func calculateNumberOfLines() {

        let layoutManager = NSLayoutManager()

        let textStorage = NSTextStorage(string: self.titleLabel!.text!)
        textStorage.addAttribute(NSFontAttributeName, value: self.titleLabel!.font, range: NSMakeRange(0, textStorage.length))

        let textContainer = NSTextContainer(size: self.titleLabel!.bounds.size)

        layoutManager.addTextContainer(textContainer)
        layoutManager.textStorage = textStorage
        guard let text = titleLabel?.text else { return }

        let numberOfLines = totalNumberOfLinesIn(text: text, currentGlyphIndex:0, currentLineNumber: 1, layoutManager: layoutManager, textContainer: textContainer)
        numberOfLinesLabel.text = "\(numberOfLines)"
    }

    func totalNumberOfLinesIn(text text: String, currentGlyphIndex glyphIndex:Int, currentLineNumber line:Int, layoutManager: NSLayoutManager, textContainer: NSTextContainer) -> Int
    {
        let maxGlyphIndex = layoutManager.glyphRangeForTextContainer(textContainer)

        let lineFragment = layoutManager.lineFragmentRectForGlyphAtIndex(glyphIndex, effectiveRange: nil)
        let glyphRange = layoutManager.glyphRangeForBoundingRect(lineFragment, inTextContainer: textContainer)

        if NSMaxRange(glyphRange) < NSMaxRange(maxGlyphIndex) {
            return totalNumberOfLinesIn(text: text, currentGlyphIndex:glyphIndex + glyphRange.length,  currentLineNumber: (line + 1), layoutManager: layoutManager, textContainer: textContainer)
        }

        return line
    }
}


class TestViewController: UIViewController{

    static let CellIdentifier = "CellIdentifier"

    var randomSizedTexts = [
        "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.\nUt enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.",
        "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. ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur?",
        "Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem",
        ", 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",
        "At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident",
        "Et harum quidem rerum facilis est et expedita distinctio",
        "Mauris id efficitur sapien. Nunc lobortis nisi ut ultricies scelerisque. Curabitur accumsan sit amet lacus in finibus. Aliquam dolor ante, rhoncus sit amet fermentum et, semper sit amet nisi. Proin pretium velit ut quam mollis fringilla. Nullam neque risus, vestibulum eget tortor sit amet, suscipit ultricies metus. In tortor ipsum, feugiat lacinia leo id, pulvinar lacinia velit. Suspendisse sit amet porta tellus, et scelerisque odio. Nam convallis sodales congue. Proin vel quam id arcu nisi non.",
    ]

    lazy var tableView: UITableView! = {
        let tableView = UITableView(frame: CGRectZero, style: .Plain)
        tableView.translatesAutoresizingMaskIntoConstraints = false
        tableView.delegate = self
        tableView.dataSource = self
        tableView.rowHeight = UITableViewAutomaticDimension
        tableView.estimatedRowHeight = 44
        self.view.addSubview(tableView)
        self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[tableView]|", options: NSLayoutFormatOptions(rawValue: 0), metrics: nil, views: ["tableView": tableView]))
        self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|[tableView]|", options: NSLayoutFormatOptions(rawValue: 0), metrics: nil, views: ["tableView": tableView]))

        return tableView
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = UIColor.whiteColor()
        tableView.registerClass(TableViewCell.self, forCellReuseIdentifier: TestViewController.CellIdentifier)
    }

}

extension TestViewController: UITableViewDataSource, UITableViewDelegate {

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier(TestViewController.CellIdentifier, forIndexPath: indexPath) as! TableViewCell
        cell.index = indexPath.row
        cell.textDetail = randomSizedTexts[indexPath.row]
        return cell
    }

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return randomSizedTexts.count
    }
}

      

        
        
        
      

    

Update: It looks like the size of the NSTextContainer based on the size of the titleLabel doesn't fit. As the size of the titleLabel is currently not entirely appropriate. It seems that manually calculating the size for the borders available to display the label gives the correct result. See Changes.