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

Note that @kurt-j's answer will not always work. In some cases, you will have to manually provide the width of label. Since these cases exist, it is a good idea to have an optional width parameter, even if you don't end up using it.

Swift 4.2:

extension UILabel {
    func calculateMaxLines(actualWidth: CGFloat?) -> Int {
        var width = frame.size.width
        if let actualWidth = actualWidth {
            width = actualWidth
        }
        let maxSize = CGSize(width: width, height: CGFloat(Float.infinity))
        let charSize = font.lineHeight
        let text = (self.text ?? "") as NSString
        let textSize = text.boundingRect(with: maxSize, options: .usesLineFragmentOrigin, attributes: [NSAttributedString.Key.font: font], context: nil)
        let linesRoundedUp = Int(ceil(textSize.height/charSize)) 
        return linesRoundedUp
    }    
}