Dynamic UITableView row height using UIStackView? - ios

Question

Surprised this isn't working out of the box, as this seems to be an important use case for stack views. I have a UITableViewCell subclass which adds a UIStackView to the contentView. I'm adding labels to the stack view in tableView(_cellForRowAtIndexPath:) and the tableview is set to use dynamic row heights, but it doesn't appear to work, at least in Xcode 7.3. I was also under the impression that hiding arranged subviews in a stack view was animatable, but that seems broken as well.
Any ideas on how to get this working correctly?
class StackCell : UITableViewCell {
enum VisualFormat: String {
case HorizontalStackViewFormat = "H:|[stackView]|"
case VerticalStackViewFormat = "V:|[stackView(>=44)]|"
}
var hasSetupConstraints = false
lazy var stackView : UIStackView! = {
let stack = UIStackView()
stack.axis = .Vertical
stack.distribution = .FillProportionally
stack.alignment = .Fill
stack.spacing = 3.0
stack.translatesAutoresizingMaskIntoConstraints = false
return stack
}()
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
contentView.addSubview(stackView)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func updateConstraints() {
if !hasSetupConstraints {
hasSetupConstraints = true
let viewsDictionary: [String:AnyObject] = ["stackView" : stackView]
var newConstraints = [NSLayoutConstraint]()
newConstraints += self.newConstraints(VisualFormat.HorizontalStackViewFormat.rawValue, viewsDictionary: viewsDictionary)
newConstraints += self.newConstraints(VisualFormat.VerticalStackViewFormat.rawValue, viewsDictionary: viewsDictionary)
addConstraints(newConstraints)
}
super.updateConstraints()
}
private func newConstraints(visualFormat: String, viewsDictionary: [String:AnyObject]) -> [NSLayoutConstraint] {
return NSLayoutConstraint.constraintsWithVisualFormat(visualFormat, options: [], metrics: nil, views: viewsDictionary)
}
class ViewController: UITableViewController {
private let reuseIdentifier = "StackCell"
private let cellClass = StackCell.self
override func viewDidLoad() {
super.viewDidLoad()
configureTableView(self.tableView)
}
private func configureTableView(tableView: UITableView) {
tableView.registerClass(cellClass, forCellReuseIdentifier: reuseIdentifier)
tableView.separatorStyle = .SingleLine
tableView.estimatedRowHeight = 88
tableView.rowHeight = UITableViewAutomaticDimension
}
private func newLabel(title: String) -> UILabel {
let label = UILabel()
label.text = title
return label
}
// MARK: - UITableView
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 4
}
override func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 44.0
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 10
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier(reuseIdentifier, forIndexPath: indexPath) as! StackCell
cell.stackView.arrangedSubviews.forEach({$0.removeFromSuperview()})
cell.stackView.addArrangedSubview(newLabel("\(indexPath.section)-\(indexPath.row)"))
cell.stackView.addArrangedSubview(newLabel("Second Label"))
cell.stackView.addArrangedSubview(newLabel("Third Label"))
cell.stackView.addArrangedSubview(newLabel("Fourth Label"))
cell.stackView.addArrangedSubview(newLabel("Fifth Label"))
return cell
}
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
let cell = tableView.cellForRowAtIndexPath(indexPath) as! StackCell
for (idx, view) in cell.stackView.arrangedSubviews.enumerate() {
if idx == 0 {
continue
}
view.hidden = !view.hidden
}
UIView.animateWithDuration(0.3, animations: {
cell.contentView.layoutIfNeeded()
tableView.beginUpdates()
tableView.endUpdates()
})
}
}

Answer 1

It seems that for this to work the constraints need to be added in the init of the UITableViewCell and added to the contentView instead of cell's view.
The working code looks like this:
import UIKit
class StackCell : UITableViewCell {
enum VisualFormat: String {
case HorizontalStackViewFormat = "H:|[stackView]|"
case VerticalStackViewFormat = "V:|[stackView(>=44)]|"
}
var hasSetupConstraints = false
lazy var stackView : UIStackView! = {
let stack = UIStackView()
stack.axis = UILayoutConstraintAxis.Vertical
stack.distribution = .FillProportionally
stack.alignment = .Fill
stack.spacing = 3.0
stack.translatesAutoresizingMaskIntoConstraints = false
stack.setContentCompressionResistancePriority(UILayoutPriorityRequired, forAxis: .Vertical)
return stack
}()
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
contentView.addSubview(stackView)
addStackConstraints()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
private func addStackConstraints() {
let viewsDictionary: [String:AnyObject] = ["stackView" : stackView]
var newConstraints = [NSLayoutConstraint]()
newConstraints += self.newConstraints(VisualFormat.HorizontalStackViewFormat.rawValue, viewsDictionary: viewsDictionary)
newConstraints += self.newConstraints(VisualFormat.VerticalStackViewFormat.rawValue, viewsDictionary: viewsDictionary)
contentView.addConstraints(newConstraints)
super.updateConstraints()
}
private func newConstraints(visualFormat: String, viewsDictionary: [String:AnyObject]) -> [NSLayoutConstraint] {
return NSLayoutConstraint.constraintsWithVisualFormat(visualFormat, options: [], metrics: nil, views: viewsDictionary)
}
}