Dynamically positioning UILabel to bottom of content view with Swift? - ios

Question

I was trying to position my dynamically created UILabels to my contentView's bottom. I'm using HTML Parser called Fuzi to catch HTML tags and creating UILabels based on them;
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([labelLeading, labelTrailing, labelTop])
}
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)
}
I tried calling my stringFromHTML function in viewDidAppear. But it positions my UILabels to far far away (they don't seem).
I want to position my labels to the bottom of the last label, see the image below;
Anyone can help? Thanks in advance!

Answer 1

Change
let labelTop = NSLayoutConstraint(item: label, attribute: .top, relatedBy: .equal, toItem: contentView, attribute: .top, multiplier: 1, constant: self.contentView.frame.origin.y)
To
if label != nil {
let labelTop = NSLayoutConstraint(item: label, attribute: .top, relatedBy: .equal, toItem: label[index], 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)
}
Because you are basically forcing each label to be at the same y position.