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metatext-app-ios-iphone-ipad/Data Sources/ExploreDataSource.swift
2021-01-30 14:27:49 -08:00

71 lines
2.5 KiB
Swift

// Copyright © 2021 Metabolist. All rights reserved.
import Combine
import Mastodon
import UIKit
import ViewModels
final class ExploreDataSource: UICollectionViewDiffableDataSource<ExploreViewModel.Section, ExploreViewModel.Item> {
private let updateQueue =
DispatchQueue(label: "com.metabolist.metatext.explore-data-source.update-queue")
private var cancellables = Set<AnyCancellable>()
init(collectionView: UICollectionView, viewModel: ExploreViewModel) {
let tagRegistration = UICollectionView.CellRegistration<TagCollectionViewCell, TagViewModel> {
$0.viewModel = $2
}
super.init(collectionView: collectionView) {
switch $2 {
case let .tag(tag):
return $0.dequeueConfiguredReusableCell(
using: tagRegistration,
for: $1,
item: viewModel.viewModel(tag: tag))
}
}
let headerRegistration = UICollectionView.SupplementaryRegistration
<ExploreSectionHeaderView>(elementKind: "Header") { [weak self] in
$0.label.text = self?.snapshot().sectionIdentifiers[$2.section].displayName
}
supplementaryViewProvider = {
$0.dequeueConfiguredReusableSupplementary(using: headerRegistration, for: $2)
}
viewModel.$trends.sink { [weak self] tags in
guard let self = self else { return }
var snapshot = NSDiffableDataSourceSnapshot<ExploreViewModel.Section, ExploreViewModel.Item>()
if !tags.isEmpty {
snapshot.appendSections([.trending])
snapshot.appendItems(tags.map(ExploreViewModel.Item.tag), toSection: .trending)
}
self.apply(snapshot, animatingDifferences: false)
}
.store(in: &cancellables)
}
override func apply(_ snapshot: NSDiffableDataSourceSnapshot<ExploreViewModel.Section, ExploreViewModel.Item>,
animatingDifferences: Bool = true,
completion: (() -> Void)? = nil) {
updateQueue.async {
super.apply(snapshot, animatingDifferences: animatingDifferences, completion: completion)
}
}
}
private extension ExploreViewModel.Section {
var displayName: String {
switch self {
case .trending:
return NSLocalizedString("explore.trending", comment: "")
case .instance:
return NSLocalizedString("explore.instance", comment: "")
}
}
}