使用 Swift 3 阅读更多/更少 [英] Read More/Less with Swift 3

问题描述

我想在段落末尾添加阅读更多".当我点击阅读更多"文本时，它应该展开并在末尾显示更少".单击较少"文本时，文本将折叠.

I want to add "Read more" at the end of the paragraph. When I click on the "Read more" text, it should be expand and display "Less" at the end. The texts will be collapsed when click on "Less" text.

我在谷歌找到了很多示例工作.但是，我不太明白，大多数项目都是用Objective-C实现的.我也在youtube上找到了.
我想知道使用 Swift 3 实现此功能的非常示例代码.
我可以在不使用任何额外库的情况下实现吗?
请帮帮我.

I find many sample work in google. But, I don't understand clearly and most projects are implemented with Objective-C. I also find it in youtube.
I would like know very sample code to implement this with Swift 3.
Can I implement without using any additional library?
Please help me.

推荐答案

• 为messageLabel
的高度限制创建一个出口
• 将阅读更多"按钮的顶部布局设置为 messageLabel

• 点击阅读更多"按钮增加高度约束常数，点击阅读更少"减少高度约束常数.

  • Create an outlet for height constraint of your messageLabel
  • Set top layout of your "Read more" button to messageLabel

  • On clicking "Read more" button increase height constraint constant, on clicking "Read less" decrease height constraint constant.

    @IBOutlet weak var btn: UIButton!
    
    @IBOutlet weak var lblHeight: NSLayoutConstraint!
    
    var isLabelAtMaxHeight = false
    
    @IBAction func btnAction(_ sender: Any) {
        if isLabelAtMaxHeight {
            btn.setTitle("Read more", for: .normal)
            isLabelAtMaxHeight = false
            lblHeight.constant = 70
        }
        else {
            btn.setTitle("Read less", for: .normal)
            isLabelAtMaxHeight = true
            lblHeight.constant = getLabelHeight(text: yourSummaryText, width: view.bounds.width, font: yourSummaryLabel.font)
        }
    }
    

  获取文本高度

      func getLabelHeight(text: String, width: CGFloat, font: UIFont) -> CGFloat {
          let lbl = UILabel(frame: .zero)
          lbl.frame.size.width = width
          lbl.font = font
          lbl.numberOfLines = 0
          lbl.text = text
          lbl.sizeToFit()
  
          return lbl.frame.size.height
      }
  

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