单元格不是使用UIViewController中的UITableViewDiffableDataSource填充的

Question

在将子类从UITableViewController更改为UIViewController之前，我的代码一直在工作。

切换的原因是我需要在tableView的顶部添加一个collectionView。

但现在这些细胞没有繁殖。快照仍在调用中，用户数组包含其内容。

不确定为什么更改为UIViewController会导致单元格停止填充。

import UIKit
private let reuseIdentifier = "UserCell"
private typealias UserDataSource = UITableViewDiffableDataSource<SearchController.Section, User>
private typealias UsersSnapshot = NSDiffableDataSourceSnapshot<SearchController.Section, User>
class SearchController: UIViewController {
// MARK: - Properties

private var tableView = UITableView()
private var users = [User]()
private var filteredUsers = [User]()
private let searchController = UISearchController(searchResultsController: nil)
private var inSearchMode: Bool {
return searchController.isActive && !searchController.searchBar.text!.isEmpty
}
private var dataSource: UserDataSource!
// MARK: - Lifecycle
override func viewDidLoad() {
super.viewDidLoad()
configureSearchController()
configureTableView()
configureDataSource()
fetchUsers()
}
// MARK: - API
private func fetchUsers() {
showLoader(true)
UserService.fetchUsers { [weak self] users in
self?.showLoader(false)
self?.users = users
self?.createSnapshot(from: users)
}
}
// MARK: - Helpers
private func configureTableView() {
view.backgroundColor = .white
tableView.register(UserCell.self, forCellReuseIdentifier: reuseIdentifier)
tableView.rowHeight = 64
}
private func configureDataSource() {
dataSource = UserDataSource(tableView: tableView, cellProvider: { (tableView, indexPath, user) -> UITableViewCell? in
guard let cell = tableView.dequeueReusableCell(withIdentifier: reuseIdentifier, for: indexPath) as? UserCell else { fatalError() }
let user = self.inSearchMode ? self.filteredUsers[indexPath.row] : self.users[indexPath.row]
cell.viewModel = UserCellViewModel(user: user)
return cell
})
}
private func configureSearchController() {
searchController.searchResultsUpdater = self
searchController.obscuresBackgroundDuringPresentation = false
searchController.hidesNavigationBarDuringPresentation = false
searchController.searchBar.placeholder = "Search"
navigationItem.searchController = searchController
definesPresentationContext = false
}
private func createSnapshot(from users: [User]) {
var snapshot = UsersSnapshot()
snapshot.appendSections([.main])
snapshot.appendItems(users)
self.dataSource.apply(snapshot, animatingDifferences: false)
}
}

// MARK: - UITableViewDelegate
extension SearchController {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
guard let nonFilteredUser = dataSource.itemIdentifier(for: indexPath) else { return }
let user = inSearchMode ? self.filteredUsers[indexPath.row] : nonFilteredUser
let controller = ProfileController(user: user)
navigationController?.pushViewController(controller, animated: true)
}
}
// MARK: - UISearchResultsUpdating
extension SearchController: UISearchResultsUpdating {
func updateSearchResults(for searchController: UISearchController) {
guard let searchText = searchController.searchBar.text?.lowercased() else { return }
filteredUsers = users.filter({$0.username.lowercased().contains(searchText)
|| $0.fullname.lowercased().contains(searchText) })
let users = searchText.isEmpty ? self.users : filteredUsers
self.createSnapshot(from: users)
}
}
// MARK: - Sections
extension SearchController {
fileprivate enum Section {
case main
}
}

Answer 1

表视图实际上没有添加到框架中，所以当我切换到UIViewController子类时，视图层次结构中实际上没有tableView。我在viewDidLoad中添加了这个，现在它是可见的。

忘记了UIViewController不会像UITableViewController子类那样自动在视图中添加tableView。

// MARK: - Lifecycle
override func viewDidLoad() {
super.viewDidLoad()
configureSearchController()
configureTableView()
configureDataSource()
fetchUsers()

view.addSubview(tableView) // What I've missed to add.
tableView.frame = view.bounds
}