Label高度自适应

 var newsTitleFrame = CGRect.init(x: marginLeft, y: marginTop, width: screenSize.width-marginLeft*2, height: 0)
        let newsTitleLabel = UILabel.init(frame: newsTitleFrame)
        newsTitleLabel.text = dict["newstitle"] as? String
        newsTitleLabel.font = UIFont.systemFont(ofSize: 15)
        newsTitleLabel.textColor = UIColor.black
        newsTitleLabel.numberOfLines = 0
        let options: NSStringDrawingOptions = .usesLineFragmentOrigin
        let str: NSString = newsTitleLabel.text! as NSString
        let boundingRect = str.boundingRect(with: newsTitleLabel.frame.size, options: options, attributes: [NSFontAttributeName:newsTitleLabel.font], context: nil)
        newsTitleFrame.size.height = boundingRect.height
        newsTitleLabel.frame = newsTitleFrame
        newsTitleLabel.lineBreakMode = .byWordWrapping
        
        newsTitleLabel.tag = newsTitleLabelTag
        
        bgView.addSubview(newsTitleLabel)