How to find actual number of lines of UILabel?

Question

How can I find the actual number of lines of a UILabel after I have initialized it with a text and a font? I have set

Answer 1

It seems that the official developer website mentions one solution Counting Lines of Text in Objc. However, it assumes you have a reference to a text view configured with a layout manager, text storage, and text container. Unfortunately, UILabel doesn't expose those to us, so we need create them with the same configuration as the UILabel.

I translated the Objc code to swift as following. It seems work well for me.

extension UILabel {
    var actualNumberOfLines: Int {
        let textStorage = NSTextStorage(attributedString: self.attributedText!)
        let layoutManager = NSLayoutManager()
        textStorage.addLayoutManager(layoutManager)
        let textContainer = NSTextContainer(size: self.bounds.size)
        textContainer.lineFragmentPadding = 0
        textContainer.lineBreakMode = self.lineBreakMode
        layoutManager.addTextContainer(textContainer)

        let numberOfGlyphs = layoutManager.numberOfGlyphs
        var numberOfLines = 0, index = 0, lineRange = NSMakeRange(0, 1)

        while index < numberOfGlyphs {
            layoutManager.lineFragmentRect(forGlyphAt: index, effectiveRange: &lineRange)
            index = NSMaxRange(lineRange)
            numberOfLines += 1
        }
        return numberOfLines
    }
}