swift 计算label中文字高度

计算label的文字高度:

func getTextHeigh(textStr :  String, font : UIFont, width : CGFloat)  -> CGFloat{ 

        let normalText : NSString = textStr as NSString

        let size = CGSize(width: width, height:1000)   //CGSizeMake(width,1000)

        let dic = NSDictionary(object: font, forKey : kCTFontAttributeName as! NSCopying)

        let stringSize = normalText.boundingRect(with: size, options: .usesLineFragmentOrigin, attributes: dic as? [NSAttributedStringKey:Any], context:nil).size

        return  stringSize.height

    }