swift-文字幅と高さの計算

// e.g.
        let kTitleFarPOIMaxWidth: CGFloat = self.view.frame.size.width - 142
        let kTitlePOIMaxHeight: CGFloat = 51
        let s = " abc'de,212(*^% abcde bacdea"
        let fontSize: CGFloat = 21
        let w: CGFloat = kTitleFarPOIMaxWidth
        let h1 = s.ga_heightForComment(fontSize: fontSize, width: w)
        let h = s.ga_heightForComment(fontSize: fontSize, width: w, maxHeight: kTitlePOIMaxHeight)
        let l = UILabel(frame: CGRect(x: 100, y: 100, width: w, height: h))
        l.font = UIFont.systemFont(ofSize: fontSize, weight: UIFontWeightMedium)
        l.text = s
        l.numberOfLines = 0
        l.backgroundColor = UIColor.yellow
        self.view.addSubview(l)


//  UIFont.systemFont(ofSize: fontSize, weight: UIFontWeightMedium)
//  weight 
extension String {
    func ga_widthForComment(fontSize: CGFloat, height: CGFloat = 15) -> CGFloat {
        let font = UIFont.systemFont(ofSize: fontSize)
        let rect = NSString(string: self).boundingRect(with: CGSize(width: CGFloat(MAXFLOAT), height: height), options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)
        return ceil(rect.width)
    }
    
    func ga_heightForComment(fontSize: CGFloat, width: CGFloat) -> CGFloat {
        let font = UIFont.systemFont(ofSize: fontSize)
        let rect = NSString(string: self).boundingRect(with: CGSize(width: width, height: CGFloat(MAXFLOAT)), options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)
        return ceil(rect.height)
    }
    
    func ga_heightForComment(fontSize: CGFloat, width: CGFloat, maxHeight: CGFloat) -> CGFloat {
        let font = UIFont.systemFont(ofSize: fontSize)
        let rect = NSString(string: self).boundingRect(with: CGSize(width: width, height: CGFloat(MAXFLOAT)), options: .usesLineFragmentOrigin, attributes: [NSFontAttributeName: font], context: nil)
        return ceil(rect.height)>maxHeight ? maxHeight : ceil(rect.height)
    }
}