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 { }

Hi together, i have truble to parse an json with an array like following: "data": [ [ 0000000000, [ { "count": 0 } ] ], [ 0000000000, [ { "count": 0 } ] ] ], Can someone help me to parse that with the this? Thanks

Hi, developers! I use DiffableDataSource for myTableView and was surprised when I found that TableView in this case caches previously created cells after (or before) a new update. It seems that this is implemented to store cell states and quickly update if the contents of the table change. Because of this mechanism, I have the following problem: my cells use reference-type view models, which in turn contain notification observers from the file upload service. The view model is connected to the cell with a closure, which is called upon notification and updates, for example, the progress scale in the cell After uploading the file, I make a new applySnapshot using similar models with cameras (but, for example, the "fileName" field is already different, so I need to change it in cell). Due to caching of cells in memory, the old view models with observers are not released, as a result, I get two observers, for two different cells, one of which is visible, and the second is not. This causes problems with UI. To summarize, my question is, is it possible to disable cell caching or clean the cache if using Diffable Data Source manually?

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.

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) } }

We use CollectionView with UICollectionViewLayout. On willDisplay we send all cells to back, and move to front supplementaryView. It works well, until iOS 17. But now both of these methods doesn't work. Does anybody know why? And any other way to resolve this problem.