如何在具有无限行的UILabel上自动换行？

Question

I have a UILabel in which the number of lines need to be set to 0 (infinite lines). But when it displays a single long word, it breaks the line by character, to form a second line. I tried to set Line breaking mode manually as such

cell.nameLbl.adjustsFontSizeToFitWidth = true
cell.nameLbl.lineBreakMode = .byWordWrapping

But the app still breaks by character. How can I fix this? Edit- I want the word font size to shrink.

Answer 1

Adjusting font size is unfortunately done per label, not per line. Wrapping does not effect it. So the result you are seeing is expected. You could split your string manually into multiple labels maybe putting them into stack view to get desired result.

What I tried was:

private func layoutText(text: String, onStackView stackView: UIStackView) {
    var words: [String] = text.components(separatedBy: .whitespaces)

    var currentLineWords: [String] = [String]()
    var currentLabel: UILabel!

    func newLabel() -> UILabel {
        let label = UILabel(frame: stackView.bounds)
        label.adjustsFontSizeToFitWidth = true
        label.minimumScaleFactor = 0.5
        return label
    }

    while words.count > 0 {
        if currentLineWords.count == 0 {
            currentLabel = newLabel()
            currentLineWords.append(words.removeFirst())
        } else {
            let newText = currentLineWords.joined(separator: " ") + " " + words[0]
            currentLabel.text = newText
            currentLabel.sizeToFit()

            if currentLabel.bounds.width > stackView.bounds.width {
                // Break line
                currentLabel.text = currentLineWords.joined(separator: " ")
                stackView.addArrangedSubview(currentLabel)
                currentLabel = nil
                currentLineWords = [String]()
            } else {
                // All good
                currentLineWords.append(words.removeFirst())
            }
        }
    }

    if currentLineWords.count > 0 {
        currentLabel.text = currentLineWords.joined(separator: " ")
        stackView.addArrangedSubview(currentLabel)
    }
}

This works pretty neatly but:

• When word is too long to fit in a line even when shrunk it will show "..." at the end
• Shrunk line still has the same height instead of having it reduced
• We are only handling whitespaces and inserting back spaces

The first 2 would probably both be solved by having manual adjustsFontSizeToFitWidth . Basically keep reducing font size until it fits or until a certain size. If "certain size" scenario is hit then simply use multiline on a label (will break by characters).

The last one just need some extra effort.

I would still not implement this for multiple reasons one of them being that it looks ugly but is still interesting.

Custom font size adjustment:

To have custom font adjustment and all the logic there is only a change when a new lien is created:

            if currentLineWords.count == 0 {
                currentLabel = newLabel()
                currentLineWords.append(words.removeFirst())

                currentLabel.text = currentLineWords.joined(separator: " ")
                currentLabel.sizeToFit()

                if currentLabel.bounds.width > stackView.bounds.width {
                    currentLabel.adjustsFontSizeToFitWidth = false

                    let originalFontSize: CGFloat = currentLabel.font.pointSize
                    var currentFontSize: CGFloat = originalFontSize
                    let minimalFontSize: CGFloat = currentLabel.minimumScaleFactor > 0.0 ? currentLabel.font.pointSize * currentLabel.minimumScaleFactor : originalFontSize

                    while currentLabel.bounds.width > stackView.bounds.width {
                        currentFontSize -= 1.0
                        if currentFontSize < minimalFontSize {
                            currentLabel.numberOfLines = 0
                            currentLabel.font = UIFont(name: currentLabel.font.fontName, size: originalFontSize)
                            break // Could not shrink it even further. USe multiline
                        }
                        currentLabel.font = UIFont(name: currentLabel.font.fontName, size: currentFontSize)
                        currentLabel.sizeToFit()
                    }

                    // Break line
                    stackView.addArrangedSubview(currentLabel)
                    currentLabel = nil
                    currentLineWords = [String]()
                }
            } 

This looks usable now. My result: