Prevent UIStackView from compressing UITableView - ios

Question

I am adding a UITableView into vertical UIStackView. That vertical UIStackView is within a UIScrollView.
However the table is not displaying unless I force an explicit Height constraint on it which I obviously don't want to do.
According to this SO question and answer UITableView not shown inside UIStackView this is because "stackview tries to compress content as much as possible"
If I add a UILabel to the StackView it is displayed fine. There is something specific about the UITableView that means it is not. I am using Xamarin and creating the UITableView in code
this.recentlyOpenedPatientsTable = new UITableView()
{
RowHeight = UITableView.AutomaticDimension,
EstimatedRowHeight = 44.0f,
AllowsMultipleSelectionDuringEditing = false,
TranslatesAutoresizingMaskIntoConstraints = false,
Editing = false,
BackgroundColor = UIColor.Clear,
TableFooterView = new UIView(),
ScrollEnabled = false,
};
The UIScrollView is pinned to the Top, Bottom, Left and Right of the View and works fine. It takes the Height I expect.
I have tried both the suggestions in this SO question and neither have worked. I find it odd that I cannot find others having this issue.
Any other suggestions?

Answer 1

Here is a very basic example, using a UITableView subclass to make it auto-size its height based on its content.
The red buttons (in a horizontal stack view) are the first arranged subView in the vertical stack view.
The table is next (green background for the cells' contentView, yellow background for a multi-line label).
And the last arranged subView is a cyan background UILabel:
Note that the vertical stack view is constrained 40-pts from Top, Leading and Trailing, and at least 40-pts from the Bottom. If you add enough rows to the table to exceed the available height, you'll have to scroll to see the additional rows.
//
// TableInStackViewController.swift
//
// Created by Don Mag on 6/24/19.
//
import UIKit
final class ContentSizedTableView: UITableView {
override var contentSize:CGSize {
didSet {
invalidateIntrinsicContentSize()
}
}
override var intrinsicContentSize: CGSize {
layoutIfNeeded()
return CGSize(width: UIView.noIntrinsicMetric, height: contentSize.height)
}
}
class TableInStackCell: UITableViewCell {
let theLabel: UILabel = {
let v = UILabel()
v.translatesAutoresizingMaskIntoConstraints = false
v.backgroundColor = .yellow
v.textAlignment = .left
v.numberOfLines = 0
return v
}()
override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
contentView.backgroundColor = .green
contentView.addSubview(theLabel)
NSLayoutConstraint.activate([
theLabel.topAnchor.constraint(equalTo: contentView.layoutMarginsGuide.topAnchor, constant: 0.0),
theLabel.bottomAnchor.constraint(equalTo: contentView.layoutMarginsGuide.bottomAnchor, constant: 0.0),
theLabel.leadingAnchor.constraint(equalTo: contentView.layoutMarginsGuide.leadingAnchor, constant: 0.0),
theLabel.trailingAnchor.constraint(equalTo: contentView.layoutMarginsGuide.trailingAnchor, constant: 0.0),
])
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
class TableInStackViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
let theStackView: UIStackView = {
let v = UIStackView()
v.translatesAutoresizingMaskIntoConstraints = false
v.axis = .vertical
v.alignment = .fill
v.distribution = .fill
v.spacing = 8
return v
}()
let addButton: UIButton = {
let v = UIButton()
v.translatesAutoresizingMaskIntoConstraints = false
v.setTitle("Add a Row", for: .normal)
v.backgroundColor = .red
return v
}()
let deleteButton: UIButton = {
let v = UIButton()
v.translatesAutoresizingMaskIntoConstraints = false
v.setTitle("Delete a Row", for: .normal)
v.backgroundColor = .red
return v
}()
let buttonsStack: UIStackView = {
let v = UIStackView()
v.axis = .horizontal
v.alignment = .fill
v.distribution = .fillEqually
v.spacing = 20
return v
}()
let theTable: ContentSizedTableView = {
let v = ContentSizedTableView()
v.translatesAutoresizingMaskIntoConstraints = false
return v
}()
let bottomLabel: UILabel = {
let v = UILabel()
v.translatesAutoresizingMaskIntoConstraints = false
v.backgroundColor = .cyan
v.textAlignment = .center
v.numberOfLines = 0
v.text = "This label is the last element in the stack view."
// prevent label from being compressed when the table gets too tall
v.setContentCompressionResistancePriority(.required, for: .vertical)
return v
}()
var theTableData: [String] = [
"Content Sized Table View",
"This row shows that the cell heights will auto-size, based on the cell content (multi-line label in this case).",
"Here is the 3rd default row",
]
var minRows = 1
let reuseID = "TableInStackCell"
override func viewDidLoad() {
super.viewDidLoad()
minRows = theTableData.count
view.addSubview(theStackView)
NSLayoutConstraint.activate([
// constrain stack view 40-pts from top, leading and trailing
theStackView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 40.0),
theStackView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor, constant: 40.0),
theStackView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor, constant: -40.0),
// constrain stack view *at least* 40-pts from bottom
theStackView.bottomAnchor.constraint(lessThanOrEqualTo: view.safeAreaLayoutGuide.bottomAnchor, constant: -40.0),
])
buttonsStack.addArrangedSubview(addButton)
buttonsStack.addArrangedSubview(deleteButton)
theStackView.addArrangedSubview(buttonsStack)
theStackView.addArrangedSubview(theTable)
theStackView.addArrangedSubview(bottomLabel)
theTable.delegate = self
theTable.dataSource = self
theTable.register(TableInStackCell.self, forCellReuseIdentifier: reuseID)
addButton.addTarget(self, action: #selector(addRow), for: .touchUpInside)
deleteButton.addTarget(self, action: #selector(deleteRow), for: .touchUpInside)
}
#objc func addRow() -> Void {
// add a row to our data source
let n = theTableData.count - minRows
theTableData.append("Added Row: \(n + 1)")
theTable.reloadData()
}
#objc func deleteRow() -> Void {
// delete a row from our data source (keeping the original rows intact)
let n = theTableData.count
if n > minRows {
theTableData.remove(at: n - 1)
theTable.reloadData()
}
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return theTableData.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: reuseID, for: indexPath) as! TableInStackCell
cell.theLabel.text = theTableData[indexPath.row]
return cell
}
}