Number of lines in UILabel in self-sizing tableview cell

Question

EDIT 2-I was able to get it to work by using a different method found in a different question (https://stackoverflow.com/a/14413484/2584268), but I also combined it with the code provided by GeneratorOfOne, and I have posted my result below. I am still running into an issue with the end goal of this, though. The goal is to have line numbers next to each line of text, sort of like in a code editor. The problem is that I need to keep a running number of lines, so if there are 3 lines in the first cell, the line numbers in the second cell should start at 4 and so on, but I don't believe I can do this because the number of lines is being calculated in the cell so I cannot return a value back to the tableview to set the text of the second label (line numbers)...any ideas?

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

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

    func calculateNumberOfLines() {

        let layoutManager = NSLayoutManager()

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

        let textContainer = NSTextContainer(size: CGSize(width:self.contentView.bounds.size.width - 56.0, height: CGFloat.max))
        layoutManager.addTextContainer(textContainer)
        layoutManager.textStorage = textStorage
        if let text = gameInfo?.text {

            let numberOfLines = getLinesArrayOfStringInLabel(gameInfo)
            lineNumbers.text = "\(startingNum)"
            for index in startingNum+1...startingNum+numberOfLines {

                lineNumbers.text = lineNumbers.text?.stringByAppendingString("\n\(index)")

            }

            endingNum = startingNum+numberOfLines
            //let numberOfLines = totalNumberOfLinesIn(text, currentGlyphIndex:0, currentLineNumber: 1, layoutManager: layoutManager, textContainer: textContainer)
            //lineNumbers.text = "\(numberOfLines)"

        } else { return }


    }

    func getLinesArrayOfStringInLabel(label: UILabel) -> Int {

        var text = label.text as! NSString
        var font = label.font
        var rect = label.frame

        var myFont = CTFontCreateWithName(font.fontName, font.pointSize, nil)
        var attrString = NSMutableAttributedString(string: text as String)
        attrString.addAttribute(String(kCTFontAttributeName), value: myFont, range: NSMakeRange(0, attrString.length))

        let frameSetter = CTFramesetterCreateWithAttributedString(attrString)

        var path = CGPathCreateMutable()
        CGPathAddRect(path, nil, CGRectMake(0,0,rect.size.width,100000))
        var frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, 0), path, nil)

        var lines = CTFrameGetLines(frame) as NSArray
        var linesArray = NSMutableArray()

        for line in lines as [AnyObject] {

            var lineRef = line as! CTLineRef
            var lineRange = CTLineGetStringRange(lineRef)
            var range = NSMakeRange(lineRange.location, lineRange.length)

            var lineString = text.substringWithRange(range)
            linesArray.addObject(lineString)

        }

        return linesArray.count
    }

I have a custom UITableViewCell subclass that is using self-sizing cells. The sizing of the cells is perfect and the label is being extended correctly. However, at run time I am trying to calculate the number of lines that the label will be extended to (I need to display the line numbers next to the label), and I am not able to achieve this. I have tried the following two methods and neither seem to be returning the correct number of lines that I am seeing when the app runs:

func lineCountForText(string: String, label: UILabel) -> Int {

        let font: UIFont = UIFont(name: "SourceCodePro-Regular", size: label.font.pointSize)!

        let rect = string.boundingRectWithSize(CGSizeMake(label.frame.width, CGFloat(MAXFLOAT)), options: NSStringDrawingOptions.UsesLineFragmentOrigin, attributes: [font : NSFontAttributeName], context: nil)

        return Int(ceil(rect.size.height/font.lineHeight))

    }

    func numberOfLinesForString(string: String, size: CGSize, font: UIFont) -> Int {
        let textStorage = NSTextStorage(string: string, attributes: [NSFontAttributeName: font])

        let textContainer = NSTextContainer(size: size)
        textContainer.lineBreakMode = .ByWordWrapping
        textContainer.maximumNumberOfLines = 0
        textContainer.lineFragmentPadding = 0

        let layoutManager = NSLayoutManager()
        layoutManager.textStorage = textStorage
        layoutManager.addTextContainer(textContainer)

        var numberOfLines = 0
        var index = 0
        var lineRange : NSRange = NSMakeRange(0, 0)
        for (; index < layoutManager.numberOfGlyphs; numberOfLines++) {
            layoutManager.lineFragmentRectForGlyphAtIndex(index, effectiveRange: &lineRange)
            index = NSMaxRange(lineRange)
        }

        return numberOfLines
    }

Am I not able to do this because it is a self-sizing cell?

EDIT-Here is the array of text that I am using:

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.",

    ]

Answer 1

Trying to use NSAttributedString:

func lineCountForLabel(label: UILabel) -> Int {

    let font: UIFont = label.font

    let attribtedString = label.attributedText.mutableCopy() as! NSMutableAttributedString
    let paragraphStyle = NSMutableParagraphStyle()
    paragraphStyle.lineBreakMode = label.lineBreakMode
    attribtedString.addAttribute(NSParagraphStyleAttributeName, value: paragraphStyle, range: NSRange(location: 0, length: attribtedString.length))

    let rect = attribtedString.boundingRectWithSize(CGSizeMake(label.frame.width, CGFloat(MAXFLOAT)),
        options: .UsesLineFragmentOrigin | .UsesFontLeading,
        context: nil)

    return Int(ceil(rect.size.height/font.lineHeight))
}

UPDATE:

You can write the type of a dictionary in shorthand form as [Key: Value], so your this line is incorrect:

let rect = string.boundingRectWithSize(xx, xx, xx, attributes: [font : NSFontAttributeName], context: nil)

change:

[font : NSFontAttributeName]

to:

[NSFontAttributeName : font]

---

UPDATE(after the question updated)

You should store a line numbers in your dataSource like this:

class MyCell: UITableViewCell {

    @IBOutlet var contentLabel: UILabel!
    @IBOutlet private var numberLabel: UILabel!
}

class MasterViewController: UITableViewController {

    var objects = [AnyObject]()

    override func viewDidLoad() {
        super.viewDidLoad()

        let addButton = UIBarButtonItem(barButtonSystemItem: .Add, target: self, action: "insertNewObject:")
        self.navigationItem.rightBarButtonItem = addButton

        self.tableView.estimatedRowHeight = 44
        self.tableView.rowHeight = UITableViewAutomaticDimension

        self.insertNewObject(self)
        self.insertNewObject(self)
        self.insertNewObject(self)
        self.insertNewObject(self)
        self.insertNewObject(self)
        self.insertNewObject(self)
        self.insertNewObject(self)
        self.insertNewObject(self)
        self.insertNewObject(self)
        self.insertNewObject(self)
    }

    func insertNewObject(sender: AnyObject) {
        var count = Int(arc4random_uniform(20)) + 1

        var string = ""
        while (count-- > 0) {
            string += "This is a test."
        }
        objects.insert(["content" : string, "lineNumber" : 0], atIndex: 0)
    }

    // MARK: - Table View

    override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return 1
    }

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

    override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! MyCell

        var object = objects[indexPath.row] as! [String : AnyObject]

        var startLineNumber = 0
        if indexPath.row > 0 {
            var pObject = objects[indexPath.row - 1] as! [String : AnyObject]
            startLineNumber = pObject["lineNumber"] as! Int
        }

        cell.contentView.setNeedsLayout()
        cell.contentView.layoutIfNeeded()

        cell.contentLabel.text = object["content"] as? String
        let lineNumber = lineCountForLabel(cell.contentLabel)  + startLineNumber
        cell.numberLabel.text = "\(lineNumber)"

        object["lineNumber"] = lineNumber
        objects[indexPath.row] = object

        return cell
    }

    func lineCountForLabel(label: UILabel) -> Int {

        let font: UIFont = label.font

        let attribtedString = label.attributedText.mutableCopy() as! NSMutableAttributedString
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.lineBreakMode = label.lineBreakMode
        attribtedString.addAttribute(NSParagraphStyleAttributeName, value: paragraphStyle, range: NSRange(location: 0, length: attribtedString.length))

        let rect = attribtedString.boundingRectWithSize(CGSizeMake(label.frame.width, CGFloat(MAXFLOAT)),
            options: .UsesLineFragmentOrigin | .UsesFontLeading,
            context: nil)

        return Int(ceil(rect.size.height/font.lineHeight))
    }

}

---

UPDATE:

There are a few problems in your demo.

Change

lastNumUsed = 1

to

lastNumUsed = 0

and change

for index in lastNumUsed+1...lastNumUsed+numLines

to

for index in lastNumUsed+1...lastNumUsed+numLines-1

Finally, the point of the issue is the gameInfo's size is correct or not. When the cellForRow executing it's superview maybe a nil, so the size of the cell and the gameInfo is incorrect. Instead, you should calculate the number of lines in willDisplayCell like so:

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

    var cell: LineNumberSubtitleCell! = tableView.dequeueReusableCellWithIdentifier("GameCell", forIndexPath: indexPath) as! LineNumberSubtitleCell

    if cell == nil {
        cell = LineNumberSubtitleCell(style: UITableViewCellStyle.Default, reuseIdentifier: "GameCell")
    }

    cell.gameInfo.text = randomSizedTexts[indexPath.row]

    return cell
}

override func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
    let cell = cell as! LineNumberSubtitleCell

    cell.contentView.setNeedsLayout()
    cell.contentView.layoutIfNeeded()

    let numLines = getLinesArrayOfStringInLabel(cell.gameInfo)
    cell.lineNumbers.text = "\(lastNumUsed)"

    if !(lineNumbersList.count > indexPath.row) {

        for index in lastNumUsed+1...lastNumUsed+numLines-1 {

            cell.lineNumbers.text = cell.lineNumbers.text?.stringByAppendingString("\n\(index)")

            if index == lastNumUsed+numLines-1 {

                lastNumUsed = index+1
                lineNumbersList.addObject(cell.lineNumbers.text!)
            }
        }
    } else {
        cell.lineNumbers.text = lineNumbersList.objectAtIndex(indexPath.row) as? String
    }
}

Calling the setNeedsLayout method forces your view to update its layout. Calling the layoutIfNeeded method force the layout system to be run now. So the gameInfo's size should be recalculated to correct.

Answer 2

You can use labelHeight/12.0f for number of lines where 12.0f is the font size being used.

Answer 3

Here is a simple example which counts the number of lines in a text.

The method goes in recursively to find the glyph index, and get a linefragment and compare if the glyph at 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 seems like setting the NSTextContainer size based on the titleLabel size is not appropriate. Since the titleLabel size is not quite appropriate at this time. It seems like manually calculating the size for the bounds available to display the label gives correct result. Please see the changes.

Answer 4

Implement dynamic height for all cells. Here is an example. In this example cell is having a label.

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {

    cellHeight = 40.0f; // Height excluding label height

    // Calculate label height
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 288, 0)];
    label.font = [UIFont systemFontOfSize:13];
    label.text = [details objectAtIndex:indexPath.row];
    label.numberOfLines = 0;
    [label sizeToFit];
    cellHeight += [PSIUtility heightForLabel:label];

    label.text = [tips objectAtIndex:indexPath.row];
    label.numberOfLines = 0;
    [label sizeToFit];

    cellHeight += [self heightForLabel:label];

    //Return cell Height
    return cellHeight;

}

- (CGFloat)heightForLabel:(UILabel *)label{

    //Calculate the expected size based on the font and linebreak mode of your label
    // FLT_MAX here simply means no constraint in height
    label.numberOfLines = 0;

    CGSize maximumLabelSize = CGSizeMake(label.frame.size.width, FLT_MAX);

    //    CGSize expectedLabelSize = [label.text sizeWithFont:label.font constrainedToSize:maximumLabelSize lineBreakMode:label.lineBreakMode];


    CGRect expectedLabelSize = [label.text boundingRectWithSize:maximumLabelSize
                                                        options:(NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingUsesFontLeading)
                                                     attributes:@{NSFontAttributeName:label.font}
                                                        context:nil];

    return expectedLabelSize.size.height;

}