metatext/View Controllers/StatusListViewController.swift
2020-09-02 02:07:09 -07:00

216 lines
8 KiB
Swift

// Copyright © 2020 Metabolist. All rights reserved.
import SwiftUI
import Combine
import ViewModels
class StatusListViewController: UITableViewController {
private let viewModel: StatusListViewModel
private let loadingTableFooterView = LoadingTableFooterView()
private var cancellables = Set<AnyCancellable>()
private var cellHeightCaches = [CGFloat: [String: CGFloat]]()
private let dataSourceQueue =
DispatchQueue(label: "com.metabolist.metatext.status-list.data-source-queue")
private lazy var dataSource: UITableViewDiffableDataSource<Int, String> = {
UITableViewDiffableDataSource(tableView: tableView) { [weak self] tableView, indexPath, statusID in
guard
let self = self,
let cell = tableView.dequeueReusableCell(
withIdentifier: String(describing: StatusTableViewCell.self),
for: indexPath) as? StatusTableViewCell
else { return nil }
cell.viewModel = self.viewModel.statusViewModel(id: statusID)
cell.delegate = self
return cell
}
}()
init(viewModel: StatusListViewModel) {
self.viewModel = viewModel
super.init(style: .plain)
}
@available(*, unavailable)
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func viewDidLoad() {
super.viewDidLoad()
for cellClass in [StatusTableViewCell.self] {
let classString = String(describing: cellClass)
tableView.register(
UINib(nibName: classString, bundle: nil),
forCellReuseIdentifier: classString)
}
tableView.dataSource = dataSource
tableView.prefetchDataSource = self
tableView.cellLayoutMarginsFollowReadableWidth = true
tableView.separatorInset = .zero
tableView.tableFooterView = UIView()
viewModel.$statusIDs
.sink { [weak self] statusIDs in
guard let self = self else { return }
var offsetFromNavigationBar: CGFloat?
if
let id = self.viewModel.maintainScrollPositionOfStatusID,
let indexPath = self.dataSource.indexPath(for: id),
let navigationBar = self.navigationController?.navigationBar {
let navigationBarMaxY = self.tableView.convert(navigationBar.bounds, from: navigationBar).maxY
offsetFromNavigationBar = self.tableView.rectForRow(at: indexPath).origin.y - navigationBarMaxY
}
self.dataSourceQueue.async {
self.dataSource.apply(statusIDs.snapshot(), animatingDifferences: false) {
if
let id = self.viewModel.maintainScrollPositionOfStatusID,
let indexPath = self.dataSource.indexPath(for: id) {
self.tableView.scrollToRow(at: indexPath, at: .top, animated: false)
if let offsetFromNavigationBar = offsetFromNavigationBar {
self.tableView.contentOffset.y -= offsetFromNavigationBar
}
}
}
}
}
.store(in: &cancellables)
viewModel.$loading
.receive(on: RunLoop.main)
.sink { [weak self] in
guard let self = self else { return }
self.tableView.tableFooterView = $0 ? self.loadingTableFooterView : UIView()
self.sizeTableHeaderFooterViews()
}
.store(in: &cancellables)
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
viewModel.request()
}
override func tableView(_ tableView: UITableView,
willDisplay cell: UITableViewCell,
forRowAt indexPath: IndexPath) {
guard let item = dataSource.itemIdentifier(for: indexPath) else { return }
var heightCache = cellHeightCaches[tableView.frame.width] ?? [String: CGFloat]()
heightCache[item] = cell.frame.height
cellHeightCaches[tableView.frame.width] = heightCache
}
override func tableView(_ tableView: UITableView, estimatedHeightForRowAt indexPath: IndexPath) -> CGFloat {
guard let item = dataSource.itemIdentifier(for: indexPath) else { return UITableView.automaticDimension }
return cellHeightCaches[tableView.frame.width]?[item] ?? UITableView.automaticDimension
}
override func tableView(_ tableView: UITableView, shouldHighlightRowAt indexPath: IndexPath) -> Bool {
guard let id = dataSource.itemIdentifier(for: indexPath) else { return true }
return id != viewModel.contextParentID
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
guard let id = dataSource.itemIdentifier(for: indexPath) else { return }
navigationController?.pushViewController(
StatusListViewController(viewModel: viewModel.contextViewModel(id: id)),
animated: true)
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
sizeTableHeaderFooterViews()
}
}
extension StatusListViewController: UITableViewDataSourcePrefetching {
func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
guard
viewModel.paginates,
let indexPath = indexPaths.last,
indexPath.section == dataSource.numberOfSections(in: tableView) - 1,
indexPath.row == dataSource.tableView(tableView, numberOfRowsInSection: indexPath.section) - 1,
let maxID = dataSource.itemIdentifier(for: indexPath)
else { return }
viewModel.request(maxID: maxID)
}
}
extension StatusListViewController: StatusTableViewCellDelegate {
func statusTableViewCellDidHaveShareButtonTapped(_ cell: StatusTableViewCell) {
guard let url = cell.viewModel?.sharingURL else { return }
share(url: url)
}
}
private extension StatusListViewController {
func share(url: URL) {
let activityViewController = UIActivityViewController(activityItems: [url], applicationActivities: nil)
present(activityViewController, animated: true, completion: nil)
}
func sizeTableHeaderFooterViews() {
// https://useyourloaf.com/blog/variable-height-table-view-header/
if let headerView = tableView.tableHeaderView {
let size = headerView.systemLayoutSizeFitting(
CGSize(width: tableView.frame.width, height: .greatestFiniteMagnitude),
withHorizontalFittingPriority: .required,
verticalFittingPriority: .fittingSizeLevel)
if headerView.frame.size.height != size.height {
headerView.frame.size.height = size.height
tableView.tableHeaderView = headerView
tableView.layoutIfNeeded()
}
}
if let footerView = tableView.tableFooterView {
let size = footerView.systemLayoutSizeFitting(
CGSize(width: tableView.frame.width, height: .greatestFiniteMagnitude),
withHorizontalFittingPriority: .required,
verticalFittingPriority: .fittingSizeLevel)
if footerView.frame.size.height != size.height {
footerView.frame.size.height = size.height
tableView.tableFooterView = footerView
tableView.layoutIfNeeded()
}
}
}
}
private extension Array where Element: Sequence, Element.Element: Hashable {
func snapshot() -> NSDiffableDataSourceSnapshot<Int, Element.Element> {
var snapshot = NSDiffableDataSourceSnapshot<Int, Element.Element>()
let sections = [Int](0..<count)
snapshot.appendSections(sections)
for section in sections {
snapshot.appendItems(self[section].map { $0 }, toSection: section)
}
return snapshot
}
}