swift判断 UILabel文字是否被折叠 是否有省略号 是否没显示全

//判断文本标签的内容是否被截断
    func isTruncated (lbl : UILabel, text : String) ->(Bool) {
        let labelText = text
        
        //计算理论上显示所有文字需要的尺寸
        let rect = CGSize(width: lbl.bounds.width, height: CGFloat.greatestFiniteMagnitude)
        let labelTextSize = (labelText as NSString)
            .boundingRect(with: rect, options: .usesLineFragmentOrigin,
                          attributes: [NSAttributedString.Key.font: lbl.font], context: nil)
        
        //计算理论上需要的行数
        let labelTextLines = Int(ceil(CGFloat(labelTextSize.height) / lbl.font.lineHeight))
        
        //实际可显示的行数
        var labelShowLines = Int(floor(CGFloat(lbl.frame.size.height) / lbl.font.lineHeight))
        if lbl.numberOfLines != 0 {
            labelShowLines = min(labelShowLines, lbl.numberOfLines)
        }
        
        //比较两个行数来判断是否需要截断
        return labelTextLines > labelShowLines
    }