swift基于yyText实现全文与收起效果

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1.创建文字

 lazy var signatureLabel: YYLabel = {
        let new = YYLabel()
        new.text = "请编辑您的个性签名，获得更大的曝光"
        new.font = UIFont.systemFont(ofSize: 14)
        new.textColor = ColorSubtitle
        new.textAlignment = .left
        new.textVerticalAlignment = .top
        new.numberOfLines = 0
        new.backgroundColor = .systemYellow
        return new
    }()

2.添加全文

  func addOpenButton() {
        Logger.log("添加全文")
        self.signatureLabel.numberOfLines = 3
        let text = NSMutableAttributedString(string: "...全文")
        let hi = YYTextHighlight()
        hi.setColor(ColorTheme)
        hi.tapAction = { containerView, text, range, rect in
            self.isExpand = !self.isExpand
            if let block = self.openLabelBlock {
                block()
            }
        }
        text.yy_font = UIFont.boldSystemFont(ofSize: 14)
        text.yy_setColor(ColorBlue, range: NSRange(location: 3, length: 2))
        text.yy_setTextHighlight(hi, range: NSRange(location: 3, length: 2))
        
        let seeMore = YYLabel()
        seeMore.attributedText = text
        seeMore.sizeToFit()
        //设置断点位置
        let truncationToken = NSAttributedString.yy_attachmentString(withContent: seeMore, contentMode: .top, attachmentSize: CGSize(width: 60, height: 16), alignTo: UIFont.boldSystemFont(ofSize: 14), alignment: YYTextVerticalAlignment.top)
        //当label空间不够展示时，添加断点的全文按钮
        self.signatureLabel.truncationToken = truncationToken
        
    }

3.添加收起

  func addPackupButton() {
        Logger.log("添加收起")
        self.signatureLabel.numberOfLines = 0
        let text = NSMutableAttributedString(string: "收起")
        
        let hi = YYTextHighlight()
        hi.setColor(ColorTheme)
        hi.tapAction = { containerView, text, range, rect in
            self.isExpand = !self.isExpand
            if let block = self.openLabelBlock {
                block()
            }
        }
        text.yy_font = UIFont.boldSystemFont(ofSize: 14)
        text.yy_setColor(ColorBlue, range: NSRange(location: 0, length: 2))
        text.yy_setTextHighlight(hi, range: NSRange(location: 0, length: 2))
        
        let attributes = self.getAttributes(signatureString)
        attributes.append(text)
        self.signatureLabel.attributedText = attributes
    }

4.计算行数高度等，可自行实现

 func getAttributes(_ content: String) -> NSMutableAttributedString {
        let attributes = NSMutableAttributedString(string: content)
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.lineSpacing = 4
        attributes.addAttributes([ .paragraphStyle: paragraphStyle], range: NSRange(location: 0, length: attributes.length))
        return attributes
    }

5.判断是否展开，可自行实现

  self.signatureLabel.attributedText = self.getAttributes(signatureString)
       //计算行数
       var attH = ComUitl.getStringHeight(signatureString, kScreenWidth-40)
       var rows = ceil(attH/14)
       //控制全文/收起
       if rows > 3 {
           Logger.log(isExpand)
           self.setExpand(isExpand)
       }
       //控制高度
       var H = attH
       if self.isExpand == false && rows > 3 {
           H = 3 * 20
       }else{
           //当3行以上，需要在句末加上“收起”占位
           let tempString = signatureString + "收起"
           attH = ComUitl.getStringHeight(tempString, kScreenWidth-40)
            rows = ceil(attH/14)
           H = rows * 20 + 10
       }
       Logger.log("行数\(rows)纯文本高度\(attH)实际高度\(H)")
       signatureLabel.snp.updateConstraints { (make) in
           make.height.equalTo(H)
       }

6.其他

 var isExpand: Bool = false
    let signatureString = "水天相接，晨雾蒙蒙笼云涛。银河转动，像无数的船只在舞动风帆。梦魂仿佛回天庭，听见天帝在对我说话。我回报天帝路途还很漫长，现在已是黄昏却还未到达。即使我学诗能写出惊人的句子，又有什么用呢？长空九万里，大鹏冲天飞正高。风啊！千万别停息，将我这一叶轻舟，直送往蓬莱三仙岛哈哈。"
 var openLabelBlock: OnListenBlock?
typealias OnListenBlock = () -> ()

        signatureLabel.snp.makeConstraints { (make) in
            make.left.equalTo(20)
            make.right.equalTo(-20)
            make.top.equalTo(titleLabel.snp.bottom).offset(13)
            make.height.equalTo(180)
            make.bottom.equalTo(-16)
        }

注意：label需要设置高度或frame,当空间不够时，才添加更多