ios - 使用 Swift 将 UILabel 动态定位到内容 View 的底部？
<p><p>我试图将我动态创建的 UILabel 定位到我的 contentView 的底部。我正在使用名为 Fuzi 的 HTML Parser 来捕获 HTML 标签并基于它们创建 UILabel；</p>
<pre><code>func stringFromHTML( _ string: String?)
{
do{
let doc = try HTMLDocument(string: string!, encoding: String.Encoding.utf8)
if let root = doc.body {
for element in root.children {
if element.tag == "h2" {
// Create new label
let label = UILabel()
label.text = element.stringValue
label.numberOfLines = 0
label.font = UIFont(name: "Avenir Next", size: 17)
label.textColor = UIColor.black
self.contentView.addSubview(label)
label.translatesAutoresizingMaskIntoConstraints = false
// Label constraints
let labelLeading = NSLayoutConstraint(item: label, attribute: .leading, relatedBy: .equal, toItem: contentView, attribute: .leading, multiplier: 1, constant: 20)
let labelTrailing = NSLayoutConstraint(item: label, attribute: .trailing, relatedBy: .equal, toItem: contentView, attribute: .trailing, multiplier: 1, constant: -20)
let labelTop = NSLayoutConstraint(item: label, attribute: .top, relatedBy: .equal, toItem: contentView, attribute: .top, multiplier: 1, constant: self.contentView.frame.origin.y)
self.contentView.addConstraints()
}
updateContentViewHeight()
}
}
}
catch{
print("html error\n",error)
}
}
func updateContentViewHeight(){
var totalContentHeight:CGFloat = 0.0
for i in self.contentView.subviews {
totalContentHeight += i.frame.height
}
let contentViewHeight:NSLayoutConstraint = NSLayoutConstraint(item: self.contentView, attribute: NSLayoutAttribute.height, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: totalContentHeight-29)
self.contentView.addConstraint(contentViewHeight)
}
</code></pre>
<p>我尝试在 viewDidAppear 中调用我的 stringFromHTML 函数。但它会将我的 UILabel 定位在很远的地方(它们似乎并不存在)。</p>
<p>我想将我的标签放在最后一个标签的底部，见下图；</p>
<p> <a href="/image/CCM53.png" rel="noreferrer noopener nofollow"><img src="/image/CCM53.png" alt="My screen..."/></a> </p>
<p>有人可以帮忙吗？提前致谢!</p></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>改变</p>
<pre><code>let labelTop = NSLayoutConstraint(item: label, attribute: .top, relatedBy: .equal, toItem: contentView, attribute: .top, multiplier: 1, constant: self.contentView.frame.origin.y)
</code></pre>
<p>到</p>
<pre><code>if label != nil {
let labelTop = NSLayoutConstraint(item: label, attribute: .top, relatedBy: .equal, toItem: label, attribute: .top, multiplier: 1, constant: 2)
} else {
let labelTop = NSLayoutConstraint(item: label, attribute: .top, relatedBy: .equal, toItem: contentView, attribute: .top, multiplier: 1, constant: self.contentView.frame.origin.y)
}
</code></pre>
<p>因为您基本上是在强制每个标签位于相同的 y 位置。</p></p>
<p style="font-size: 20px;">关于ios - 使用 Swift 将 UILabel 动态定位到内容 View 的底部？，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/40446971/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/40446971/
</a>
</p>
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