GetFontSizeAfterLableAdjustedAuto.swift

    myLabel.backgroundColor = UIColor.greenColor()
    myLabel.text = "What Do I Want to Do?(Select One)"
    myLabel.adjustsFontSizeToFitWidth = true
    myLabel.minimumScaleFactor = 0.1
    
    let attributes = [NSFontAttributeName : myLabel.font]
    let attributedString = NSMutableAttributedString(string:textString, attributes:attributes)
    let context = NSStringDrawingContext()
    context.minimumScaleFactor = myLabel.minimumScaleFactor
    
    attributedString.boundingRectWithSize(
      myLabel.bounds.size,
      options: .UsesLineFragmentOrigin,
      context: context)
    
    print("actual context after drawing: \(context.actualScaleFactor)")
    
    let actualFontSize = myLabel.font.pointSize * context.actualScaleFactor
    print("actualFontSize = \(actualFontSize)")