How to figure out the font size of a UILabel when -adjustsFontSizeToFitWidth is set to YES?

Question

When myLabel.adjustsFontSizeToFitWidth = YES, UILabel will adjust the font size automatically in case the text is too long for the label. For example, if my lab

Answer 1

Swift 5

For one-line UILabel

extension UILabel {

    var actualFontSize: CGFloat {
    //initial label
     let fullSizeLabel = UILabel()
     fullSizeLabel.font = self.font
     fullSizeLabel.text = self.text
     fullSizeLabel.sizeToFit()

     var actualFontSize: CGFloat = self.font.pointSize * (self.bounds.size.width / fullSizeLabel.bounds.size.width);

    //correct, if new font size bigger than initial
     actualFontSize = actualFontSize < self.font.pointSize ? actualFontSize : self.font.pointSize;

     return actualFontSize
    }

}

Getting the actual font size is then as simple as:

let currentLabelFontSize = myLabel.actualFontSize