The last cell in UITableView always has the same height as the tallest cell in the table? - swift

Question

I have a UITableView that displays comments. The last cell always has the same height as the tallest cell in the UITableView and I do not know why. With reference to the image below, it can be seen that the height of the last custom object (LabelWithPadding) that holds the comment is the same height as the tallest custom object in the same table. Please can someone advise?
class CommentOnPostTableView: UITableView, UITableViewDataSource, UITableViewDelegate{
var items: [Comment]?
var post: ResearchPost?
let cellIDB = "commentCellId"
init(frame: CGRect, style: UITableView.Style, sourceData: [Comment], postContent: ResearchPost) {
super.init(frame: frame, style: style)
items = sourceData
post = postContent
self.dataSource = self
self.delegate = self
self.register(CommentTableViewCell.self, forCellReuseIdentifier: cellIDB)
//self.separatorStyle = .none
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
/**Delegate functions*/
extension CommentOnPostTableView{
/***Number of cells*/
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let dataSource = items{
return dataSource.count
}else{
return 0
}
}
/***Create Cell*/
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
guard let dataSource = items else{return UITableViewCell.init()}
let cell = tableView.dequeueReusableCell(withIdentifier: cellIDB, for: indexPath) as! CommentTableViewCell
cell.dataObject = dataSource[indexPath.row]
return cell
}
class CommentTableViewCell: UITableViewCell {
var commentLabel: LabelWithPadding!
var imgView: UIImageView = {
let view = UIImageView()
view.backgroundColor = UIColor.black
view.contentMode = .scaleAspectFit
view.translatesAutoresizingMaskIntoConstraints = false
return view
}()
var nameLabel: UILabel = {
let label = UILabel()
label.font = .boldSystemFont(ofSize: 11)
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
var dataObject: Comment?{
didSet{
if let data = dataObject{
guard
let image = data.imageOfCommentor,
let name = data.name,
let comment = data.comment else{return}
imgView.image = image
nameLabel.text = name
let padding = UIEdgeInsets.init(top: 3, left: 5, bottom: 3, right: 5)
commentLabel = LabelWithPadding.init(frame: .zero, with: padding)
commentLabel.translatesAutoresizingMaskIntoConstraints = false
commentLabel.label.text = comment
setupViews()
}
}
}
....
// Auto layout constraints
private func setupViews(){
let c = contentView.safeAreaLayoutGuide
contentView.addSubview(imgView)
contentView.addSubview(nameLabel)
contentView.addSubview(commentLabel)
imgView.topAnchor.constraint(equalTo: c.topAnchor, constant: borderSpace).isActive = true
imgView.leadingAnchor.constraint(equalTo: c.leadingAnchor, constant: borderSpace).isActive = true
imgView.widthAnchor.constraint(equalTo: c.widthAnchor, multiplier: 0.08).isActive = true
imgView.heightAnchor.constraint(equalTo: c.widthAnchor, multiplier: 0.08).isActive = true
nameLabel.topAnchor.constraint(equalTo: c.topAnchor, constant: borderSpace).isActive = true
nameLabel.leadingAnchor.constraint(equalTo: imgView.trailingAnchor, constant: 10).isActive = true
nameLabel.trailingAnchor.constraint(equalTo: c.trailingAnchor, constant: -borderSpace).isActive = true
commentLabel.topAnchor.constraint(equalTo: nameLabel.bottomAnchor, constant: viewSpace).isActive = true
commentLabel.widthAnchor.constraint(equalTo: nameLabel.widthAnchor).isActive = true
commentLabel.trailingAnchor.constraint(equalTo: c.trailingAnchor, constant: -borderSpace).isActive = true
commentLabel.bottomAnchor.constraint(equalTo: c.bottomAnchor).isActive = true
commentLabel.label.font = UIFont.systemFont(ofSize: 12)
commentLabel.label.numberOfLines = 0
commentLabel.label.lineBreakMode = .byWordWrapping
commentLabel.layer.cornerRadius = 7
commentLabel.layer.masksToBounds = true
commentLabel.backgroundColor = UIColor.appGrayExtraLightGray
}
}
Custom Class:
class LabelWithPadding: UIView {
var padding: UIEdgeInsets!
let label: UILabel = {
let label = UILabel()
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
init(frame: CGRect, with padding: UIEdgeInsets) {
super.init(frame: frame)
self.padding = padding
setupView()
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
private func setupView(){
self.addSubview(label)
label.topAnchor.constraint(equalTo: self.topAnchor, constant: padding.top).isActive = true
label.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -padding.bottom).isActive = true
label.leadingAnchor.constraint(equalTo: self.leadingAnchor, constant: padding.left).isActive = true
label.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: -padding.bottom).isActive = true
}
}

Answer 1

First of all, I couldn't find where you update constraints.
When you use tableView.dequeueReusableCell, you may get the old cell, so you should update old constraints (or remove old constratints and add new ones). You may read it in docs.
You should add variable to store old constraints:
var oldConstraints: [NSLayoutConstraint] = []
And should deactivate old constraints and add new constraints in setupView():
NSLayoutConstraint.deactivate(oldConstraints)
let constraints = [
imgView.topAnchor.constraint(equalTo: c.topAnchor, constant: borderSpace),
imgView.leadingAnchor.constraint(equalTo: c.leadingAnchor, constant: borderSpace),
imgView.widthAnchor.constraint(equalTo: c.widthAnchor, multiplier: 0.08),
imgView.heightAnchor.constraint(equalTo: c.widthAnchor, multiplier: 0.08),
nameLabel.topAnchor.constraint(equalTo: c.topAnchor, constant: borderSpace),
nameLabel.leadingAnchor.constraint(equalTo: imgView.trailingAnchor, constant: 10),
nameLabel.trailingAnchor.constraint(equalTo: c.trailingAnchor, constant: -borderSpace),
commentLabel.topAnchor.constraint(equalTo: nameLabel.bottomAnchor, constant: viewSpace),
commentLabel.widthAnchor.constraint(equalTo: nameLabel.widthAnchor),
commentLabel.trailingAnchor.constraint(equalTo: c.trailingAnchor, constant: -borderSpace),
commentLabel.bottomAnchor.constraint(equalTo: c.bottomAnchor)
]
NSLayoutConstraint.activate(constraints)
oldConstraints = constraints
Also you shouldn't add subviews every time you update dataObject in CommentTableViewCell, because they could have already been added.
In conclusion, you should add subview to contentView just once and update the constraints every time you update dataObject. I gave you an example how to solve your issue.
You could also use prepareForReuse() to prepare the cell for reuse:
If a UITableViewCell object is reusable—that is, it has a reuse
identifier—this method is invoked just before the object is returned
from the UITableView method dequeueReusableCellWithIdentifier:.