Question

我想在最后用Read More / Read Less创建段落（标签中）。我是iPhone应用程序开发的初学者。

这是我的代码...... 我在else条件中遇到错误。该错误是＆＃34; NSLayoutConstraint类型的值＆＃34;没有会员＆＃39; font＆＃39;＆＃34;在lbl.contant = getheight ....

@IBOutlet weak var lbl: NSLayoutConstraint!

@IBOutlet weak var btn: UIButton!        

var isLabelAtMaxHeight = false

@IBAction func ButtonAction(_ sender: Any) {
    if isLabelAtMaxHeight {
        btn.setTitle("Read more", for: .normal)
        isLabelAtMaxHeight = false
        lbl.constant = 70
    }
    else {
        btn.setTitle("Read less", for: .normal)
        isLabelAtMaxHeight = true
        lbl.constant = getHeightOfLabel(text:"Isn't it? How to do? I'm sorry I don't know how to solve this exactly. :( – May Phyu Feb 20 at 11:16 No, i dont mean like that. When you set text to label then U have to find height of label then assign that height to label with setting property number of lines = 0 – Jitendra Modi Feb 20 at 11:31" , width:
            view.bounds.width, font: lbl.font)
    }
}



func getHeightOfLabel(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
}

Answer 1

为paragraphLabel创建高度约束的出口。
设置＆＃34;阅读更多＆＃34;的顶部布局按钮到paragraphLabel。

点击＆＃34;了解更多＆＃34;按钮增加高度约束常数，点击＆＃34;少阅读＆＃34;减少高度约束常数。

@IBOutlet weak var btn: UIButton!
@IBOutlet weak var yourParagraphLabel: UILabel!
@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 = getHeightOfLabel(text: yourParagraphText, width: 
   view.bounds.width, font: yourParagraphLabel.font)
}
}

获取文字的高度

func getHeightOfLabel(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
}

如何在最后使用Read More / Read Less创建段落（标签中）？

1 个答案: