UIStackView sizeToFit doesn't work as expected - ios

Question

I've configured a test playground with a UITableView and an instance of UIStackView as its header.
The stackView contains 10 UILabels.
The problem is that after calling stackView.sizeToFit() the stackView doesn't resize itself to fit all the labels and its size is zero.
I have to manually set the size of the UIStackView to fix this issue, which defeats the purpose of the UIStackView.
Here is the code of the test Xcode Playground, so you could reproduce it in your environment:
//: A UIKit based Playground for presenting user interface
import UIKit
import PlaygroundSupport
class TestTableViewController: UITableViewController {
private lazy var searchController = UISearchController(searchResultsController: nil)
private lazy var stackView: UIStackView = {
let s = UIStackView()
s.axis = .vertical
for i in 0...10 {
let l = UILabel()
l.text = "text \(i)"
s.addArrangedSubview(l)
}
return s
}()
override func viewDidLoad() {
super.viewDidLoad()
tableView.register(UITableViewCell.self, forCellReuseIdentifier: "reuseIdentifier")
configureTableView()
configureSearchController()
}
private func configureTableView() {
tableView.tableHeaderView = stackView
stackView.sizeToFit()
tableView.tableHeaderView?.sizeToFit() // Doesn't work!!!!!!!
tableView.tableHeaderView?.frame.size = CGSize(width: 9, height: 100)
}
private func configureSearchController() {
// searchController.searchResultsUpdater = self
searchController.dimsBackgroundDuringPresentation = false
searchController.searchBar.placeholder = NSLocalizedString("Choose template",
comment: "Choose template")
}
// MARK: - Table view data source
override func numberOfSections(in tableView: UITableView) -> Int {
// #warning Incomplete implementation, return the number of sections
return 2
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of rows
return 7
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath)
cell.textLabel?.text = "\(indexPath.row)"
return cell
}
}
let nc = UINavigationController(rootViewController: TestTableViewController())
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = nc
Setting size manually achieves the desired result:
private func configureTableView() {
tableView.tableHeaderView = stackView
tableView.tableHeaderView?.frame.size = CGSize(width: 0, height: 400)
}

Answer 1

Table header views need a little extra help... This may work for you.
private func configureTableView() {
tableView.tableHeaderView = stackView
sizeHeaderToFit(tableView: tableView)
}
private func sizeHeaderToFit(tableView: UITableView) {
if let headerView = tableView.tableHeaderView {
let height = headerView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize).height
var frame = headerView.frame
frame.size.height = height
headerView.frame = frame
tableView.tableHeaderView = headerView
headerView.setNeedsLayout()
headerView.layoutIfNeeded()
}
}