swift3.0计算label,button的文字大小 rect size

//计算文字大小
    class func getTextRectSize(text: Nsstring,font: UIFont,size: CGSize) -> CGRect {
        let attributes = [NSFontAttributeName: font]
        let option = NsstringDrawingOptions.usesLineFragmentOrigin
        let rect:CGRect = text.boundingRect(with: size,options: option,attributes: attributes,context: nil)
        return rect;
    }
}