Swift 3 - Adjust Font Size to Fit Width, Multiple Lines

Question

I have a UILabel and it is set to 42.0 pt font, and the width of the label is set using autoconstraints based on factors other than the label itself (aka the things to the right

Answer 1

@Krunal's answer helped me but it doesn't work when you have unknown number of lines so here's the solution I came up with. You can also set the maximum and minimum font size. Hope this helps someone!

Swift 2.2 - Sorry, haven't migrated to Swift 3 yet.

func setFontForLabel(label:UILabel, maxFontSize:CGFloat, minFontSize:CGFloat, maxLines:Int) {

    var numLines: Int = 1
    var textSize: CGSize = CGSizeZero
    var frameSize: CGSize = CGSizeZero
    var font: UIFont = UIFont.systemFontOfSize(maxFontSize)

    frameSize = label.frame.size

    textSize = (label.text! as NSString).sizeWithAttributes([NSFontAttributeName: font])

    // Determine number of lines
    while ((textSize.width/CGFloat(numLines)) / (textSize.height * CGFloat(numLines)) > frameSize.width / frameSize.height) && numLines < maxLines {
        numLines += 1
    }

    label.font = font
    label.adjustsFontSizeToFitWidth = true
    label.numberOfLines = numLines
    label.minimumScaleFactor = minFontSize/maxFontSize
}