I thought I could easily display a toolbar in UIKit, but I was wrong, or at least I can't do so without getting "Unable to simultaneously satisfy constraints." console messages. Here is my code: import UIKit class ViewController: UIViewController { let toolbar = UIToolbar() override func viewDidLoad() { super.viewDidLoad() view.backgroundColor = .systemBackground toolbar.items = [ UIBarButtonItem(title: "Title", style: .plain, target: nil, action: nil), UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil) ] view.addSubview(toolbar) toolbar.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ toolbar.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor), toolbar.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor), toolbar.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor), toolbar.heightAnchor.constraint(equalToConstant: 44) ]) } } And here is the console log: Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) ( "<NSAutoresizingMaskLayoutConstraint:0x600002107b10 h=--& v=--& _UIToolbarContentView:0x104008e40.height == 0 (active)>", "<NSLayoutConstraint:0x600002122e90 V:|-(0)-[_UIButtonBarStackView:0x10250d8b0] (active, names: '|':_UIToolbarContentView:0x104008e40 )>", "<NSLayoutConstraint:0x600002121ef0 _UIButtonBarStackView:0x10250d8b0.bottom == _UIToolbarContentView:0x104008e40.bottom (active)>", "<NSLayoutConstraint:0x600002107a70 UIButtonLabel:0x10250f280.centerY == _UIModernBarButton:0x1027059c0'Title'.centerY + 1.5 (active)>", "<NSLayoutConstraint:0x60000210ea30 'TB_Baseline_Baseline' _UIModernBarButton:0x1027059c0'Title'.lastBaseline == UILayoutGuide:0x600003b0ca80'UIViewLayoutMarginsGuide'.bottom (active)>", "<NSLayoutConstraint:0x60000210ea80 'TB_Top_Top' V:|-(>=0)-[_UIModernBarButton:0x1027059c0'Title'] (active, names: '|':_UIButtonBarButton:0x102607120 )>", "<NSLayoutConstraint:0x60000210e8f0 'UIButtonBar.maximumAlignmentSize' _UIButtonBarButton:0x102607120.height == UILayoutGuide:0x600003b00380'UIViewLayoutMarginsGuide'.height (active)>", "<NSLayoutConstraint:0x60000212c960 'UIView-bottomMargin-guide-constraint' V:[UILayoutGuide:0x600003b00380'UIViewLayoutMarginsGuide']-(0)-| (active, names: '|':_UIButtonBarStackView:0x10250d8b0 )>", "<NSLayoutConstraint:0x60000210ec60 'UIView-bottomMargin-guide-constraint' V:[UILayoutGuide:0x600003b0ca80'UIViewLayoutMarginsGuide']-(11)-| (active, names: '|':_UIButtonBarButton:0x102607120 )>", "<NSLayoutConstraint:0x60000212d6d0 'UIView-topMargin-guide-constraint' V:|-(0)-[UILayoutGuide:0x600003b00380'UIViewLayoutMarginsGuide'] (active, names: '|':_UIButtonBarStackView:0x10250d8b0 )>" ) Will attempt to recover by breaking constraint <NSLayoutConstraint:0x600002107a70 UIButtonLabel:0x10250f280.centerY == _UIModernBarButton:0x1027059c0'Title'.centerY + 1.5 (active)> Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful. Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) ( "<NSAutoresizingMaskLayoutConstraint:0x600002106710 h=--& v=--& _UIToolbarContentView:0x104008e40.width == 0 (active)>", "<NSLayoutConstraint:0x600002120b40 H:|-(0)-[_UIButtonBarStackView:0x10250d8b0] (active, names: '|':_UIToolbarContentView:0x104008e40 )>", "<NSLayoutConstraint:0x600002122e40 H:[_UIButtonBarStackView:0x10250d8b0]-(0)-| (active, names: '|':_UIToolbarContentView:0x104008e40 )>", "<NSLayoutConstraint:0x60000210eda0 'TB_Leading_Leading' H:|-(16)-[_UIModernBarButton:0x1027059c0'Title'] (active, names: '|':_UIButtonBarButton:0x102607120 )>", "<NSLayoutConstraint:0x60000210eb70 'TB_Trailing_Trailing' H:[_UIModernBarButton:0x1027059c0'Title']-(16)-| (active, names: '|':_UIButtonBarButton:0x102607120 )>", "<NSLayoutConstraint:0x60000210e580 'UISV-canvas-connection' UILayoutGuide:0x600003b00380'UIViewLayoutMarginsGuide'.leading == _UIButtonBarButton:0x102607120.leading (active)>", "<NSLayoutConstraint:0x60000210e5d0 'UISV-canvas-connection' UILayoutGuide:0x600003b00380'UIViewLayoutMarginsGuide'.trailing == UIView:0x10400e480.trailing (active)>", "<NSLayoutConstraint:0x60000210e9e0 'UISV-spacing' H:[_UIButtonBarButton:0x102607120]-(0)-[UIView:0x10400e480] (active)>", "<NSLayoutConstraint:0x60000212c820 'UIView-leftMargin-guide-constraint' H:|-(0)-[UILayoutGuide:0x600003b00380'UIViewLayoutMarginsGuide'](LTR) (active, names: '|':_UIButtonBarStackView:0x10250d8b0 )>", "<NSLayoutConstraint:0x60000212ca00 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x600003b00380'UIViewLayoutMarginsGuide']-(0)-|(LTR) (active, names: '|':_UIButtonBarStackView:0x10250d8b0 )>" ) Will attempt to recover by breaking constraint <NSLayoutConstraint:0x60000210eb70 'TB_Trailing_Trailing' H:[_UIModernBarButton:0x1027059c0'Title']-(16)-| (active, names: '|':_UIButtonBarButton:0x102607120 )> Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful. I tried giving the toolbar a frame rather than constraints, and also to not give it an explicit height. The only thing that works is to comment out UIBarButtonItem(title: "Title", style: .plain, target: nil, action: nil), which isn't really a solution. What am I doing wrong?

The following Swift UIKit code produces the warning "Cannot access property 'authController' with a non-sendable type 'AuthController' from non-isolated deinit; this is an error in Swift 6": import UIKit class AuthFormNavC: UINavigationController { let authController: AuthController init(authController: AuthController) { self.authController = authController super.init(rootViewController: ConsentVC()) } required init?(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been implemented") } deinit { authController.signInAnonymouslyIfNecessary() } } Swift 5.10, Xcode 15.3 with complete strict concurrency checking. What is the workaround? Please don't ask me why I'm doing what I'm doing or anything unrelated to the question. If you're wondering why I want to call authController.signInAnonymouslyIfNecessary() when the navigation controller is denitialized, my goal is to call it when the navigation controller is dismissed (or popped), and I think that the deinitializer of a view controller is the only method that is called if and only if the view controller is being dismissed (or popped) in my case. I tried observing variables like isViewLoaded in the past using KVO but I couldn't get it to work passing any combination of options in observe(_:options:changeHandler:).

If you run the following UIKit app and tap the view controller's right bar button item, the footerText property will change. How should I update the collection view's footer to display the updated footerText? class ViewController: UIViewController { var collectionView: UICollectionView! var footerText = "Initial footer text" var dataSource: UICollectionViewDiffableDataSource<Section, String>! var snapshot: NSDiffableDataSourceSnapshot<Section, String> { var snapshot = NSDiffableDataSourceSnapshot<Section, String>() snapshot.appendSections(Section.allCases) snapshot.appendItems(["A", "a"], toSection: .first) return snapshot } enum Section: CaseIterable { case first } override func viewDidLoad() { super.viewDidLoad() configureHierarchy() configureDataSource() } func configureHierarchy() { navigationItem.rightBarButtonItem = .init(title: "Change footer text", style: .plain, target: self, action: #selector(changeFooterText)) collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: createLayout()) view.addSubview(collectionView) collectionView.autoresizingMask = [.flexibleHeight, .flexibleWidth] } @objc func changeFooterText() { footerText = "Secondary footer text" } func configureDataSource() { let cellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, String> { cell, indexPath, itemIdentifier in var contentConfiguration = UIListContentConfiguration.cell() contentConfiguration.text = itemIdentifier cell.contentConfiguration = contentConfiguration } dataSource = .init(collectionView: collectionView) { collectionView, indexPath, itemIdentifier in collectionView.dequeueConfiguredReusableCell(using: cellRegistration, for: indexPath, item: itemIdentifier) } configureSupplementaryViewProvider() dataSource.apply(self.snapshot) } func configureSupplementaryViewProvider() { let headerRegistration = UICollectionView.SupplementaryRegistration<UICollectionViewListCell>(elementKind: UICollectionView.elementKindSectionHeader) { headerView, elementKind, indexPath in var contentConfiguration = UIListContentConfiguration.cell() contentConfiguration.text = "Header \(indexPath.section)" headerView.contentConfiguration = contentConfiguration } let footerRegistration = UICollectionView.SupplementaryRegistration<UICollectionViewListCell>(elementKind: UICollectionView.elementKindSectionFooter) { [weak self] headerView, elementKind, indexPath in guard let self else { return } var contentConfiguration = UIListContentConfiguration.cell() contentConfiguration.text = self.footerText headerView.contentConfiguration = contentConfiguration } dataSource.supplementaryViewProvider = { collectionView, kind, indexPath in if kind == UICollectionView.elementKindSectionHeader { collectionView.dequeueConfiguredReusableSupplementary(using: headerRegistration, for: indexPath) } else if kind == UICollectionView.elementKindSectionFooter { collectionView.dequeueConfiguredReusableSupplementary(using: footerRegistration, for: indexPath) } else { nil } } } func createLayout() -> UICollectionViewLayout { UICollectionViewCompositionalLayout { section, layoutEnvironment in var config = UICollectionLayoutListConfiguration(appearance: .insetGrouped) config.headerMode = .supplementary config.footerMode = .supplementary return NSCollectionLayoutSection.list(using: config, layoutEnvironment: layoutEnvironment) } } } What I've tried to do in footerText's didSet: Reconfiguring the supplementary view provider: var footerText = "Initial footer text" { didSet { configureSupplementaryViewProvider() } } Also re-applying the snapshot: var footerText = "Initial footer text" { didSet { configureSupplementaryViewProvider() dataSource.apply(self.snapshot) } } Also re-configuring the items: var footerText = "Initial footer text" { didSet { configureSupplementaryViewProvider() dataSource.apply(self.snapshot, animatingDifferences: true) var snapshot = dataSource.snapshot() snapshot.reconfigureItems(snapshot.itemIdentifiers) dataSource.apply(snapshot, animatingDifferences: false) } }

Please run the following UIKit app. It displays a collection view with compositional layout (list layout) and diffable data source. import UIKit class ViewController: UIViewController { var bool = false { didSet { var snapshot = dataSource.snapshot() snapshot.reconfigureItems(snapshot.itemIdentifiers) dataSource.apply(snapshot, animatingDifferences: true) } } var collectionView: UICollectionView! var dataSource: UICollectionViewDiffableDataSource<String, String>! var snapshot: NSDiffableDataSourceSnapshot<String, String> { var snapshot = NSDiffableDataSourceSnapshot<String, String>() snapshot.appendSections(["section"]) snapshot.appendItems(["id"]) return snapshot } override func viewDidLoad() { super.viewDidLoad() configureHierarchy() configureDataSource() } func configureHierarchy() { collectionView = .init(frame: view.bounds, collectionViewLayout: createLayout()) view.addSubview(collectionView) collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight] } func createLayout() -> UICollectionViewLayout { let configuration = UICollectionLayoutListConfiguration(appearance: .insetGrouped) return UICollectionViewCompositionalLayout.list(using: configuration) } func configureDataSource() { let cellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, String> { [weak self] cell, indexPath, itemIdentifier in guard let self else { return } let _switch = UISwitch() cell.accessories = [ .customView(configuration: .init( customView: _switch, placement: .trailing()) ), // .disclosureIndicator() ] _switch.isOn = bool _switch.addTarget(self, action: #selector(toggleBool), for: .valueChanged) } dataSource = .init(collectionView: collectionView) { collectionView, indexPath, itemIdentifier in collectionView.dequeueConfiguredReusableCell(using: cellRegistration, for: indexPath, item: itemIdentifier) } dataSource.apply(self.snapshot, animatingDifferences: false) } @objc func toggleBool() { bool.toggle() } } When you tap on the switch, it lags. If you uncomment .disclosureIndicator() and tap on the switch, it doesn't lag. How do I make it so that the switch doesn't lag without having a disclosure indicator in the cell? Note: while it would solve the issue, I would prefer not to declare the switch at the class level, as I don't want to declare all my controls, which could be quite a lot, at the view controller level in my real app. Edit: declaring the switch at the configureDataSource() level also fixes it, but it would still be inconvenient to declare many switches, say of a list with n elements, at that level.

The following UIKit swift app uses a table view with 2 sections. The first section displays a custom cell with a text view, which was added to the cell’s contentView and anchored to the ladder’s layoutMarginsGuide’s top, bottom, leading and trailing anchors. The second section displays a custom cell that is like the former but with a text field instead of a text view. Both sections have titles defined in the tableView(_:cellForRowAt:) method. If you run the app, you will see that the text view’s text is not vertically aligned to it’s section’s title, whereas the text field’s is. How do I align the text view’s text as well? import UIKit class ViewController: UIViewController { let tableView = UITableView() override func viewDidLoad() { super.viewDidLoad() view.addSubview(tableView) tableView.frame = view.bounds tableView.autoresizingMask = [.flexibleWidth, .flexibleHeight] tableView.dataSource = self tableView.register(TextViewCell.self, forCellReuseIdentifier: TextViewCell.identifier) tableView.register(TextFieldCell.self, forCellReuseIdentifier: TextFieldCell.identifier) } } extension ViewController: UITableViewDataSource { func numberOfSections(in tableView: UITableView) -> Int { 2 } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { 1 } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { if indexPath.section == 0 { tableView.dequeueReusableCell(withIdentifier: TextViewCell.identifier, for: indexPath) } else { tableView.dequeueReusableCell(withIdentifier: TextFieldCell.identifier, for: indexPath) } } func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? { "Title \(section)" } } extension UITableViewCell { static var identifier: String { "\(Self.self)" } } class TextViewCell: UITableViewCell { let textView: UITextView = { let tv = UITextView() tv.text = "Text view" tv.font = .preferredFont(forTextStyle: .title2) tv.backgroundColor = .systemRed tv.isScrollEnabled = false return tv }() override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) { super.init(style: style, reuseIdentifier: reuseIdentifier) contentView.addSubview(textView) textView.pin(to: contentView.layoutMarginsGuide) } required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") } } class TextFieldCell: UITableViewCell { let textField: UITextField = { let tf = UITextField() tf.text = "Text field" tf.backgroundColor = .systemBlue return tf }() override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) { super.init(style: style, reuseIdentifier: reuseIdentifier) contentView.addSubview(textField) textField.pin(to: contentView.layoutMarginsGuide) } required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") } } Here's how the pin(to:) function is defined in case you're wondering: import UIKit extension UIView { func pin( to object: CanBePinnedTo, top: CGFloat = 0, bottom: CGFloat = 0, leading: CGFloat = 0, trailing: CGFloat = 0 ) { self.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ self.topAnchor.constraint(equalTo: object.topAnchor, constant: top), self.bottomAnchor.constraint(equalTo: object.bottomAnchor, constant: bottom), self.leadingAnchor.constraint(equalTo: object.leadingAnchor, constant: leading), self.trailingAnchor.constraint(equalTo: object.trailingAnchor, constant: trailing), ]) } } @MainActor protocol CanBePinnedTo { var topAnchor: NSLayoutYAxisAnchor { get } var bottomAnchor: NSLayoutYAxisAnchor { get } var leadingAnchor: NSLayoutXAxisAnchor { get } var trailingAnchor: NSLayoutXAxisAnchor { get } } extension UIView: CanBePinnedTo { } extension UILayoutGuide: CanBePinnedTo { }

The following is a UIKit app that uses a collection view with list layout and a diffable data source. It displays one section that has 10 empty cells and then final cell whose content view contains a text view, that is pinned to the content view's layout margins guide. The text view's scrolling is set to false, so that the line collectionView.selfSizingInvalidation = .enabledIncludingConstraints will succeed at making the text view's cell resize automatically and animatedly as the text changes. import UIKit class ViewController: UIViewController { var collectionView: UICollectionView! var dataSource: UICollectionViewDiffableDataSource<String, Int>! let textView: UITextView = { let tv = UITextView() tv.text = "Text" tv.isScrollEnabled = false return tv }() override func viewDidLoad() { super.viewDidLoad() configureHierarchy() configureDataSource() if #available(iOS 16.0, *) { collectionView.selfSizingInvalidation = .enabledIncludingConstraints } } func configureHierarchy() { collectionView = .init(frame: .zero, collectionViewLayout: createLayout()) view.addSubview(collectionView) collectionView.frame = view.bounds collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight] } func createLayout() -> UICollectionViewLayout { let configuration = UICollectionLayoutListConfiguration(appearance: .insetGrouped) return UICollectionViewCompositionalLayout.list(using: configuration) } func configureDataSource() { let cellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, Int> { _, _, _ in } let textViewCellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, Int> { [weak self] cell, _, _ in guard let self else { return } cell.contentView.addSubview(textView) textView.pin(to: cell.contentView.layoutMarginsGuide) } dataSource = .init(collectionView: collectionView) { collectionView, indexPath, itemIdentifier in if indexPath.row == 10 { collectionView.dequeueConfiguredReusableCell(using: textViewCellRegistration, for: indexPath, item: itemIdentifier) } else { collectionView.dequeueConfiguredReusableCell(using: cellRegistration, for: indexPath, item: itemIdentifier) } } var snapshot = NSDiffableDataSourceSnapshot<String, Int>() snapshot.appendSections(["section"]) snapshot.appendItems(Array(0...10)) dataSource.apply(snapshot) } } extension UIView { func pin( to object: CanBePinnedTo, top: CGFloat = 0, bottom: CGFloat = 0, leading: CGFloat = 0, trailing: CGFloat = 0 ) { self.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ self.topAnchor.constraint(equalTo: object.topAnchor, constant: top), self.bottomAnchor.constraint(equalTo: object.bottomAnchor, constant: bottom), self.leadingAnchor.constraint(equalTo: object.leadingAnchor, constant: leading), self.trailingAnchor.constraint(equalTo: object.trailingAnchor, constant: trailing), ]) } } @MainActor protocol CanBePinnedTo { var topAnchor: NSLayoutYAxisAnchor { get } var bottomAnchor: NSLayoutYAxisAnchor { get } var leadingAnchor: NSLayoutXAxisAnchor { get } var trailingAnchor: NSLayoutXAxisAnchor { get } } extension UIView: CanBePinnedTo { } extension UILayoutGuide: CanBePinnedTo { } How do I make the UI move to accomodate the keyboard once you tap on the text view and also when the text view changes size, by activating the view.keyboardLayoutGuide.topAnchor constraint, as shown in the WWDC21 video "Your guide to keyboard layout"? My code does not resize the text view on iOS 15, only on iOS 16+, so clearly the solution may allow the UI to adjust to text view changes on iOS 16+ only. Recommended, modern, approach: Not recommended, old, approach: I've tried to say view.keyboardLayoutGuide.topAnchor.constraint(equalTo: textView.bottomAnchor).isActive = true in the text view cell registration, as well as view.keyboardLayoutGuide.topAnchor.constraint(equalTo: collectionView.bottomAnchor).isActive = true in viewDidLoad(), but both of these approaches fail (Xcode 15.3 iPhone 15 Pro simulator with iOS 17.4, physical iPhone SE on iOS 15.8).

The following is a UIKit app with a collection view with one section, whose supplementary view sports a search bar. When you type, it often resigns first responder. import UIKit class ViewController: UIViewController { let words = ["foo", "bar"] var filteredWords = ["foo", "bar"] { didSet { dataSource.apply(self.snapshot) } } var collectionView: UICollectionView! var dataSource: UICollectionViewDiffableDataSource<String, String>! var snapshot: NSDiffableDataSourceSnapshot<String, String> { var snapshot = NSDiffableDataSourceSnapshot<String, String>() snapshot.appendSections(["main"]) snapshot.appendItems(filteredWords) return snapshot } override func viewDidLoad() { super.viewDidLoad() navigationItem.rightBarButtonItem = .init(title: "Apply", style: .plain, target: self, action: #selector(apply)) configureHierarchy() configureDataSource() } @objc func apply() { dataSource.apply(self.snapshot) } func configureHierarchy() { collectionView = .init(frame: .zero, collectionViewLayout: createLayout()) view.addSubview(collectionView) collectionView.frame = view.bounds collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight] } func createLayout() -> UICollectionViewLayout { UICollectionViewCompositionalLayout { section, layoutEnvironment in var config = UICollectionLayoutListConfiguration(appearance: .insetGrouped) config.headerMode = .supplementary return NSCollectionLayoutSection.list(using: config, layoutEnvironment: layoutEnvironment) } } func configureDataSource() { let cellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, String> { _, _, _ in } dataSource = .init(collectionView: collectionView) { collectionView, indexPath, itemIdentifier in collectionView.dequeueConfiguredReusableCell(using: cellRegistration, for: indexPath, item: itemIdentifier) } let searchbarHeaderRegistration = UICollectionView.SupplementaryRegistration<SearchBarCell>(elementKind: UICollectionView.elementKindSectionHeader) { cell, elementKind, indexPath in cell.searchBar.delegate = self } dataSource.supplementaryViewProvider = { collectionView, kind, indexPath in collectionView.dequeueConfiguredReusableSupplementary(using: searchbarHeaderRegistration, for: indexPath) } dataSource.apply(self.snapshot, animatingDifferences: false) } } extension ViewController: UISearchBarDelegate { func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) { DispatchQueue.main.async { [weak self] in guard let self else { return } filteredWords = words.filter { $0.hasPrefix(searchText) } } } func searchBarTextDidEndEditing(_ searchBar: UISearchBar) { DispatchQueue.main.async { [weak self] in guard let self else { return } filteredWords = words } } } class SearchBarCell: UICollectionViewListCell { let searchBar = UISearchBar() override init(frame: CGRect) { super.init(frame: frame) contentView.addSubview(searchBar) searchBar.pinToSuperview() } required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") } } extension UIView { func pin( to object: CanBePinnedTo, top: CGFloat = 0, bottom: CGFloat = 0, leading: CGFloat = 0, trailing: CGFloat = 0 ) { self.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ self.topAnchor.constraint(equalTo: object.topAnchor, constant: top), self.bottomAnchor.constraint(equalTo: object.bottomAnchor, constant: bottom), self.leadingAnchor.constraint(equalTo: object.leadingAnchor, constant: leading), self.trailingAnchor.constraint(equalTo: object.trailingAnchor, constant: trailing), ]) } func pinToSuperview( top: CGFloat = 0, bottom: CGFloat = 0, leading: CGFloat = 0, trailing: CGFloat = 0, file: StaticString = #file, line: UInt = #line ) { guard let superview = self.superview else { print(">> \(#function) failed in file: \(String.localFilePath(from: file)), at line: \(line): could not find \(Self.self).superView.") return } self.pin(to: superview, top: top, bottom: bottom, leading: leading, trailing: trailing) } func pinToSuperview(constant c: CGFloat = 0, file: StaticString = #file, line: UInt = #line) { self.pinToSuperview(top: c, bottom: -c, leading: c, trailing: -c, file: file, line: line) } } @MainActor protocol CanBePinnedTo { var topAnchor: NSLayoutYAxisAnchor { get } var bottomAnchor: NSLayoutYAxisAnchor { get } var leadingAnchor: NSLayoutXAxisAnchor { get } var trailingAnchor: NSLayoutXAxisAnchor { get } } extension UIView: CanBePinnedTo { } extension UILayoutGuide: CanBePinnedTo { } extension String { static func localFilePath(from fullFilePath: StaticString = #file) -> Self { URL(fileURLWithPath: "\(fullFilePath)").lastPathComponent } } By the way if you remove the dispatch blocks, the app simply crashes complaining that you're trying to apply datasource snapshots from both the main queue and other queues. Xcode 15.3 iOS 17.4 simulator, MacBook Air M1 8GB macOS Sonoma 14.4.1

Please run the following UIKit app. It uses a collection view with compositional layout (list layout) and a diffable data source. The collection view has one section with one row. The cell contains a text field that is pinned to its contentView. import UIKit class ViewController: UIViewController { var collectionView: UICollectionView! var dataSource: UICollectionViewDiffableDataSource<String, String>! override func viewDidLoad() { super.viewDidLoad() configureHierarchy() configureDataSource() } func configureHierarchy() { collectionView = .init(frame: .zero, collectionViewLayout: createLayout()) view.addSubview(collectionView) collectionView.frame = view.bounds } func createLayout() -> UICollectionViewLayout { UICollectionViewCompositionalLayout { section, layoutEnvironment in let config = UICollectionLayoutListConfiguration(appearance: .insetGrouped) return NSCollectionLayoutSection.list(using: config, layoutEnvironment: layoutEnvironment) } } func configureDataSource() { let cellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, String> { cell, indexPath, itemIdentifier in let textField = UITextField() textField.placeholder = "Placeholder" textField.font = .systemFont(ofSize: 100) cell.contentView.addSubview(textField) textField.pinToSuperview() } dataSource = .init(collectionView: collectionView) { collectionView, indexPath, itemIdentifier in collectionView.dequeueConfiguredReusableCell(using: cellRegistration, for: indexPath, item: itemIdentifier) } var snapshot = NSDiffableDataSourceSnapshot<String, String>() snapshot.appendSections(["main"]) snapshot.appendItems(["demo"]) dataSource.apply(snapshot, animatingDifferences: false) } } extension UIView { func pin( to object: CanBePinnedTo, top: CGFloat = 0, bottom: CGFloat = 0, leading: CGFloat = 0, trailing: CGFloat = 0 ) { self.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ self.topAnchor.constraint(equalTo: object.topAnchor, constant: top), self.bottomAnchor.constraint(equalTo: object.bottomAnchor, constant: bottom), self.leadingAnchor.constraint(equalTo: object.leadingAnchor, constant: leading), self.trailingAnchor.constraint(equalTo: object.trailingAnchor, constant: trailing), ]) } func pinToSuperview( top: CGFloat = 0, bottom: CGFloat = 0, leading: CGFloat = 0, trailing: CGFloat = 0, file: StaticString = #file, line: UInt = #line ) { guard let superview = self.superview else { print(">> \(#function) failed in file: \(String.localFilePath(from: file)), at line: \(line): could not find \(Self.self).superView.") return } self.pin(to: superview, top: top, bottom: bottom, leading: leading, trailing: trailing) } func pinToSuperview(constant c: CGFloat = 0, file: StaticString = #file, line: UInt = #line) { self.pinToSuperview(top: c, bottom: -c, leading: c, trailing: -c, file: file, line: line) } } @MainActor protocol CanBePinnedTo { var topAnchor: NSLayoutYAxisAnchor { get } var bottomAnchor: NSLayoutYAxisAnchor { get } var leadingAnchor: NSLayoutXAxisAnchor { get } var trailingAnchor: NSLayoutXAxisAnchor { get } } extension UIView: CanBePinnedTo { } extension UILayoutGuide: CanBePinnedTo { } extension String { static func localFilePath(from fullFilePath: StaticString = #file) -> Self { URL(fileURLWithPath: "\(fullFilePath)").lastPathComponent } } Unfortunately, as soon as I insert a leading view in the cell: let cellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, String> { cell, indexPath, itemIdentifier in let contentView = cell.contentView let leadingView = UIView() leadingView.backgroundColor = .systemRed let textField = UITextField() textField.placeholder = "Placeholder" textField.font = .systemFont(ofSize: 100) contentView.addSubview(leadingView) contentView.addSubview(textField) leadingView.translatesAutoresizingMaskIntoConstraints = false textField.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ leadingView.centerYAnchor.constraint(equalTo: contentView.layoutMarginsGuide.centerYAnchor), leadingView.leadingAnchor.constraint(equalTo: contentView.layoutMarginsGuide.leadingAnchor), leadingView.widthAnchor.constraint(equalTo: contentView.layoutMarginsGuide.heightAnchor), leadingView.heightAnchor.constraint(equalTo: contentView.layoutMarginsGuide.heightAnchor), textField.topAnchor.constraint(equalTo: contentView.topAnchor), textField.bottomAnchor.constraint(equalTo: contentView.bottomAnchor), textField.leadingAnchor.constraint(equalTo: leadingView.trailingAnchor, constant: 16), textField.trailingAnchor.constraint(equalTo: contentView.layoutMarginsGuide.trailingAnchor), textField.heightAnchor.constraint(greaterThanOrEqualToConstant: 44) ]) } the cell does not self-size, and in particular it does not accomodate the text field: What would be the best way to make the cell resize automatically?

I can't fit the post here, so here's the link to it on stack overflow: https://stackoverflow.com/questions/78419812/reconfigure-custom-content-configuration

Searching for my very title (including the quotes) generated no results on Google. If you run this UIKit app and tap the right bar button item: class ViewController: UIViewController { var boolean = false { didSet { var snapshot = self.snapshot snapshot.reconfigureItems(snapshot.itemIdentifiers) // if you comment this out the app doesn't crash dataSource.apply(snapshot) } } var snapshot: NSDiffableDataSourceSnapshot<String, String> { var snapshot = NSDiffableDataSourceSnapshot<String, String>() snapshot.appendSections(["main"]) snapshot.appendItems(boolean ? ["one"] : ["one", "two"]) return snapshot } var collectionView: UICollectionView! var dataSource: UICollectionViewDiffableDataSource<String, String>! override func viewDidLoad() { super.viewDidLoad() configureHierarchy() configureDataSource() } func configureHierarchy() { collectionView = .init(frame: .zero, collectionViewLayout: createLayout()) view.addSubview(collectionView) collectionView.frame = view.bounds navigationItem.rightBarButtonItem = .init( title: "Toggle boolean", style: .plain, target: self, action: #selector(toggleBoolean) ) } @objc func toggleBoolean() { boolean.toggle() } func createLayout() -> UICollectionViewLayout { UICollectionViewCompositionalLayout { section, layoutEnvironment in let config = UICollectionLayoutListConfiguration(appearance: .insetGrouped) return NSCollectionLayoutSection.list(using: config, layoutEnvironment: layoutEnvironment) } } func configureDataSource() { let cellRegistration1 = UICollectionView.CellRegistration<UICollectionViewListCell, String> { cell, indexPath, itemIdentifier in } let cellRegistration2 = UICollectionView.CellRegistration<UICollectionViewListCell, String> { cell, indexPath, itemIdentifier in } dataSource = .init(collectionView: collectionView) { [unowned self] collectionView, indexPath, itemIdentifier in if indexPath.row == 0 && boolean { collectionView.dequeueConfiguredReusableCell(using: cellRegistration1, for: indexPath, item: itemIdentifier) } else { collectionView.dequeueConfiguredReusableCell(using: cellRegistration2, for: indexPath, item: itemIdentifier) } } dataSource.apply(self.snapshot, animatingDifferences: false) } } it crashes with that error message. The app uses a collection view with list layout and a diffable data source. It has one section, which should show one row if boolean is true, two if it's false. When boolean changes, the collection view should also reconfigure its items (in my real app, that's needed to update the shown information). If you comment out snapshot.reconfigureItems(snapshot.itemIdentifiers), the app no longer crashes. What's the correct way of reconfiguring the items of a diffable data source then? iOS 17.5, iPhone 15 Pro simulator, Xcode 15.4, macOS 17.5, MacBook Air M1 8GB.

I want to display an Apple map in my UIKit app, but if I try to do so with UIKit I get concurrency-related warnings (Xcode 15.4 with strict concurrency warnings enabled) that I couldn't find a proper solution to. So I opted for SwiftUI, and for the iOS 17 approach, specifically, (WWDC23). The following code displays a map with a marker. If you look at the Map initializer, you can see that a map camera position and a map selection are specified. If you run the app, however, you can't actually select the marker, unless you uncomment .tag(mapItem). import SwiftUI import MapKit struct MapView: View { @State private var mapCameraPosition: MapCameraPosition = .automatic @State private var mapSelection: MKMapItem? let mapItem = MKMapItem( placemark: .init( coordinate: .init( latitude: 37, longitude: -122 ) ) ) var body: some View { Map( position: $mapCameraPosition, selection: $mapSelection ) { Marker(item: mapItem) // .tag(mapItem) } .onChange(of: mapSelection) { _, newSelection in print("onChange") // never prints if let _ = newSelection { print("selected") // never prints } } } } If you give another tag, like 1, the code once again doesn't work. Is that really the way to go (that is, is my code with fine once you uncomment .tag(mapItem))? If not, how do I make a map with selectable MKMapItems in iOS 17? iOS 17.5, iPhone 15 Pro simulator, Xcode 15.4, macOS 14.5, MacBook Air M1 8GB.

Please note that for this app to be able show you your location on the map you need to enable it to ask for permission to track the user's location, in the project's targets' info: Here's also a video that illustrates the lag: https://youtube.com/shorts/DSl-umGxs20?feature=share. That being said, if you run this SwiftUI app and allow it to track your location, tap the MapUserLocationButton and press the buttons at the bottom, you'll see that the map lags: import SwiftUI import MapKit import CoreLocation struct ContentView: View { let currentLocationManager = CurrentUserLocationManager() let mapLocationsManager = MapLocationsManager() @State private var mapCameraPosition: MapCameraPosition = .automatic var body: some View { Map( position: $mapCameraPosition ) .safeAreaInset(edge: .bottom) { VStack { if mapLocationsManager.shouldAllowSearches { Button("First button") { mapLocationsManager.shouldAllowSearches = false } } Button("Second button") { mapLocationsManager.shouldAllowSearches = true } } .frame(maxWidth: .infinity) .padding() } .mapControls { MapUserLocationButton() } } } @Observable class MapLocationsManager { var shouldAllowSearches = false } // MARK: - Location related code - class CurrentUserLocationManager: NSObject { var locationManager: CLLocationManager? override init() { super.init() startIfNecessary() } func startIfNecessary() { if locationManager == nil { locationManager = .init() locationManager?.delegate = self } else { print(">> \(Self.self).\(#function): method called redundantly: locationManager had already been initialized") } } }; extension CurrentUserLocationManager: CLLocationManagerDelegate { func locationManagerDidChangeAuthorization(_ manager: CLLocationManager) { checkLocationAuthorization() } }; extension CurrentUserLocationManager { private func checkLocationAuthorization() { guard let locationManager else { return } switch locationManager.authorizationStatus { case .notDetermined: locationManager.requestWhenInUseAuthorization() case .restricted: print("Your location is restricted") case .denied: print("Go into setting to change it") case .authorizedAlways, .authorizedWhenInUse, .authorized: // locationManager.startUpdatingLocation() break @unknown default: break } } } I've also tried in a UIKit app (by just embedding ContentView in a view controller), with the same results: import UIKit import MapKit import SwiftUI import CoreLocation class ViewController: UIViewController { let currentLocationManager = CurrentUserLocationManager() override func viewDidLoad() { super.viewDidLoad() currentLocationManager.startIfNecessary() let hostingController = UIHostingController( rootView: MapView() ) addChild(hostingController) hostingController.view.frame = view.bounds hostingController.view.autoresizingMask = [.flexibleWidth, .flexibleHeight] view.addSubview(hostingController.view) hostingController.didMove(toParent: self) } } extension ViewController { struct MapView: View { let mapLocationsManager = MapLocationsManager() @State private var mapCameraPosition: MapCameraPosition = .automatic var body: some View { Map( position: $mapCameraPosition ) .safeAreaInset(edge: .bottom) { VStack { if mapLocationsManager.shouldAllowSearches { Button("First button") { mapLocationsManager.shouldAllowSearches = false } } Button("Second button") { mapLocationsManager.shouldAllowSearches = true } } .frame(maxWidth: .infinity) .padding() } .mapControls { MapUserLocationButton() } } } } extension ViewController { @Observable class MapLocationsManager { var shouldAllowSearches = false } } class CurrentUserLocationManager: NSObject { var locationManager: CLLocationManager? func startIfNecessary() { if locationManager == nil { locationManager = .init() locationManager?.delegate = self } else { print(">> \(Self.self).\(#function): method called redundantly: locationManager had already been initialized") } } }; extension CurrentUserLocationManager: CLLocationManagerDelegate { func locationManagerDidChangeAuthorization(_ manager: CLLocationManager) { checkLocationAuthorization() } }; extension CurrentUserLocationManager { private func checkLocationAuthorization() { guard let locationManager else { return } switch locationManager.authorizationStatus { case .notDetermined: locationManager.requestWhenInUseAuthorization() case .restricted: print("Your location is restricted") case .denied: print("Go into setting to change it") case .authorizedAlways, .authorizedWhenInUse, .authorized: // locationManager.startUpdatingLocation() break @unknown default: break } } } If you don't center the map in the user's location, you might see an occasiona lag, but it seems to me that this only happens once. How do I avoid these lags altogether? Xcode 15.4

If you run the following UIKit app and tap on the button, you can see that it only updates its color if you hold on it for a bit, instead of immediately (as happens in the second app) (iOS 17.5, iPhone 15 Pro simulator, Xcode 15.4). This app consists of a view controller with a table view with one cell, which has a CheckoutButton instance constrained to its contentView top, bottom, leading and trailing anchors. The checkout button uses UIButton.Configuration to set its appearance, and update it based on its state. import UIKit class ViewController: UIViewController { let tableView = UITableView() let checkoutButton = CheckoutButton() override func viewDidLoad() { super.viewDidLoad() // table view setup view.addSubview(tableView) tableView.frame = view.bounds tableView.autoresizingMask = [.flexibleHeight, .flexibleWidth] tableView.dataSource = self tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell") } } extension ViewController: UITableViewDataSource { func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { 1 } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) cell.contentView.addSubview(checkoutButton) checkoutButton.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ checkoutButton.topAnchor.constraint(equalTo: cell.contentView.topAnchor), checkoutButton.bottomAnchor.constraint(equalTo: cell.contentView.bottomAnchor), checkoutButton.leadingAnchor.constraint(equalTo: cell.contentView.leadingAnchor), checkoutButton.trailingAnchor.constraint(equalTo: cell.contentView.trailingAnchor) ]) return cell } } class CheckoutButton: UIButton { override init(frame: CGRect) { super.init(frame: frame) var configuration = UIButton.Configuration.plain() var attributeContainer = AttributeContainer() attributeContainer.font = .preferredFont(forTextStyle: .headline) attributeContainer.foregroundColor = .label configuration.attributedTitle = .init("Checkout", attributes: attributeContainer) self.configuration = configuration let configHandler: UIButton.ConfigurationUpdateHandler = { button in switch button.state { case .selected, .highlighted: button.configuration?.background.backgroundColor = .systemCyan case .disabled: button.configuration?.background.backgroundColor = .systemGray4 default: button.configuration?.background.backgroundColor = .systemBlue } } self.configurationUpdateHandler = configHandler } required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") } } In this second app, instead, the selection of the button is immediately reflected in its appearance: import UIKit class ViewController: UIViewController { let button = CheckoutButton() override func viewDidLoad() { super.viewDidLoad() view.addSubview(button) button.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ button.centerXAnchor.constraint(equalTo: view.centerXAnchor), button.centerYAnchor.constraint(equalTo: view.centerYAnchor), button.widthAnchor.constraint(equalToConstant: 300), button.heightAnchor.constraint(equalToConstant: 44) ]) } } class CheckoutButton: UIButton { override init(frame: CGRect) { super.init(frame: frame) var configuration = UIButton.Configuration.plain() var attributeContainer = AttributeContainer() attributeContainer.font = .preferredFont(forTextStyle: .headline) attributeContainer.foregroundColor = .label configuration.attributedTitle = .init("Checkout", attributes: attributeContainer) self.configuration = configuration let configHandler: UIButton.ConfigurationUpdateHandler = { button in switch button.state { case .selected, .highlighted: button.configuration?.background.backgroundColor = .systemCyan case .disabled: button.configuration?.background.backgroundColor = .systemGray4 default: button.configuration?.background.backgroundColor = .systemBlue } } self.configurationUpdateHandler = configHandler } required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") } } This app consists of a view controller with just a button: no table view unlike in the first app. How do I make the button show its selection as soon as it's tapped, no matter if it's in a table view cell or on its own?

Here is a screenshot of the app: And here follows the code: it's a view controller with a collection view with plain list layout and a diffable data source. It has 1 section with 2 rows. The 1st row's content configuration is UIListContentConfiguration.cell(), and it has some text. The 2nd row has an empty content configuration instead. As you can see, if you run the app, the separator insets are different for the two rows. Did I make a mistake? If this is expected behavior instead, is there an easy fix? import UIKit class ViewController: UIViewController { var collectionView: UICollectionView! var dataSource: UICollectionViewDiffableDataSource<String, String>! var snapshot: NSDiffableDataSourceSnapshot<String, String> { var snapshot = NSDiffableDataSourceSnapshot<String, String>() snapshot.appendSections(["main"]) snapshot.appendItems(["one", "two"]) return snapshot } override func viewDidLoad() { super.viewDidLoad() configureHierarchy() configureDataSource() } func configureHierarchy() { collectionView = .init( frame: view.bounds, collectionViewLayout: createLayout() ) view.addSubview(collectionView) collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight] } func createLayout() -> UICollectionViewLayout { return UICollectionViewCompositionalLayout { section, layoutEnvironment in let config = UICollectionLayoutListConfiguration(appearance: .plain) return NSCollectionLayoutSection.list(using: config, layoutEnvironment: layoutEnvironment) } } func configureDataSource() { let firstCellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, String> { cell, indexPath, itemIdentifier in var contentConfiguration = UIListContentConfiguration.cell() contentConfiguration.text = "Hello" cell.contentConfiguration = contentConfiguration } let secondCellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, String> { cell, indexPath, itemIdentifier in } let emptyCellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, String> { cell, indexPath, itemIdentifier in } dataSource = .init(collectionView: collectionView) { collectionView, indexPath, itemIdentifier in switch itemIdentifier { case "one": collectionView.dequeueConfiguredReusableCell(using: firstCellRegistration, for: indexPath, item: itemIdentifier) case "two": collectionView.dequeueConfiguredReusableCell(using: secondCellRegistration, for: indexPath, item: itemIdentifier) default: collectionView.dequeueConfiguredReusableCell(using: emptyCellRegistration, for: indexPath, item: itemIdentifier) } } dataSource.apply(self.snapshot, animatingDifferences: false) } } Xcode 15.4, iPhone 15 Pro simulator, iOS 17.5, MacBook Air M1 8GB, macOS 14.5.

Sample app The following is a UIKit app that displays a collection view with list layout and diffable data source (one section, one row). class ViewController: UIViewController { var collectionView: UICollectionView! var dataSource: UICollectionViewDiffableDataSource<String, String>! override func viewDidLoad() { super.viewDidLoad() configureHierarchy() configureDataSource() } func configureHierarchy() { collectionView = .init(frame: .zero, collectionViewLayout: createLayout()) view.addSubview(collectionView) collectionView.frame = view.bounds collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight] } func createLayout() -> UICollectionViewLayout { UICollectionViewCompositionalLayout { section, layoutEnvironment in let config = UICollectionLayoutListConfiguration(appearance: .insetGrouped) return NSCollectionLayoutSection.list(using: config, layoutEnvironment: layoutEnvironment) } } func configureDataSource() { let cellRegistration = UICollectionView.CellRegistration<UICollectionViewListCell, String> { cell, indexPath, itemIdentifier in var backgroundConfiguration = UIBackgroundConfiguration.listGroupedCell() backgroundConfiguration.backgroundColor = .systemBlue cell.backgroundConfiguration = backgroundConfiguration } dataSource = .init(collectionView: collectionView) { collectionView, indexPath, itemIdentifier in collectionView.dequeueConfiguredReusableCell(using: cellRegistration, for: indexPath, item: itemIdentifier) } var snapshot = NSDiffableDataSourceSnapshot<String, String>() snapshot.appendSections(["main"]) snapshot.appendItems(["demo"]) dataSource.apply(snapshot, animatingDifferences: false) } } Problem If you tap on the row, it doesn't look like it gets selected: the line backgroundConfiguration.backgroundColor = .systemBlue breaks the cell's default background color transformer. Question Given that my goal is to have my cell manifest its selection exactly like usual (meaning exactly as it would without the line backgroundConfiguration.backgroundColor = .systemBlue), that the details of how a cell usually does so are likely not public, that I would like to set a custom background color for my cell and that I would want to configure its appearance using configurations, since I seem to understand that that is the way to go from iOS 14 onwards, does anybody know how to achieve my goal by resetting something to whatever it was before I said backgroundConfiguration.backgroundColor = .systemBlue? What I've tried and didn't work: Setting the collection view's delegate and specifying that you can select any row Setting the color transformer to .grayscale Setting the cell's backgroundConfiguration to UIBackgroundConfiguration.listGroupedCell().updated(for: cell.configurationState) Setting the color transformer to cell.defaultBackgroundConfiguration().backgroundColorTransformer Using collection view controllers (and setting collectionView.clearsSelectionOnViewWillAppear to false) Setting the cell's automaticallyUpdatesBackgroundConfiguration to false and then back to true Putting the cell's configuration code inside a configurationUpdateHandler Combinations of the approaches above Setting the color transformer to UIBackgroundConfiguration.listGroupedCell().backgroundColorTransformer and cell.backgroundConfiguration?.backgroundColorTransformer (they're both nil) Workaround 1: use a custom color transformer var backgroundConfiguration = UIBackgroundConfiguration.listGroupedCell() backgroundConfiguration.backgroundColorTransformer = .init { _ in if cell.configurationState.isSelected || cell.configurationState.isHighlighted || cell.configurationState.isFocused { .systemRed } else { .systemBlue } } cell.backgroundConfiguration = backgroundConfiguration Workaround 2: don't use a background configuration You can set the cell's selectedBackgroundView, like so: let v = UIView() v.backgroundColor = .systemBlue cell.selectedBackgroundView = v You won't be able to use custom background content configurations though and might want to use background views instead: var contentConfiguration = UIListContentConfiguration.cell() contentConfiguration.text = "Hello" cell.contentConfiguration = contentConfiguration let v = UIView() v.backgroundColor = .systemBlue cell.backgroundView = v let bv = UIView() bv.backgroundColor = .systemRed cell.selectedBackgroundView = bv Consideration on the workarounds Both workarounds seem to also not break this code, which deselects cells on viewWillAppear(_:) and was taken and slightly adapted from Apple's Modern Collection Views project (e.g. EmojiExplorerViewController.swift): override func viewWillAppear(_ animated: Bool) { super.viewWillAppear(animated) deselectSelectedItems(animated: animated) } func deselectSelectedItems(animated: Bool) { if let indexPath = collectionView.indexPathsForSelectedItems?.first { if let coordinator = transitionCoordinator { coordinator.animate(alongsideTransition: { [weak self] context in self?.collectionView.deselectItem(at: indexPath, animated: true) }) { [weak self] (context) in if context.isCancelled { self?.collectionView.selectItem(at: indexPath, animated: false, scrollPosition: []) } } } else { collectionView.deselectItem(at: indexPath, animated: animated) } } } (Collection view controllers don't sport all of that logic out of the box, even though their clearsSelectionOnViewWillAppear property is true by default.)