Add loading indicator to DiffableTimelineLikeTableViewController

Tusker.xcodeproj/project.pbxproj

@@ -50,6 +50,7 @@
 		D623A5412635FB3C0095BD04 /* PollOptionView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D623A5402635FB3C0095BD04 /* PollOptionView.swift */; };
 		D623A543263634100095BD04 /* PollOptionCheckboxView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D623A542263634100095BD04 /* PollOptionCheckboxView.swift */; };
 		D625E4822588262A0074BB2B /* DraggableTableViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D625E4812588262A0074BB2B /* DraggableTableViewCell.swift */; };
+		D6262C9A28D01C4B00390C1F /* LoadingTableViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6262C9928D01C4B00390C1F /* LoadingTableViewCell.swift */; };
 		D626493523BD94CE00612E6E /* CompositionAttachmentData.swift in Sources */ = {isa = PBXBuildFile; fileRef = D626493423BD94CE00612E6E /* CompositionAttachmentData.swift */; };
 		D626493823C0FD0000612E6E /* AllPhotosTableViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D626493623C0FD0000612E6E /* AllPhotosTableViewCell.swift */; };
 		D626493923C0FD0000612E6E /* AllPhotosTableViewCell.xib in Resources */ = {isa = PBXBuildFile; fileRef = D626493723C0FD0000612E6E /* AllPhotosTableViewCell.xib */; };
@@ -397,6 +398,7 @@
 		D623A5402635FB3C0095BD04 /* PollOptionView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PollOptionView.swift; sourceTree = "<group>"; };
 		D623A542263634100095BD04 /* PollOptionCheckboxView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PollOptionCheckboxView.swift; sourceTree = "<group>"; };
 		D625E4812588262A0074BB2B /* DraggableTableViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DraggableTableViewCell.swift; sourceTree = "<group>"; };
+		D6262C9928D01C4B00390C1F /* LoadingTableViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LoadingTableViewCell.swift; sourceTree = "<group>"; };
 		D626493423BD94CE00612E6E /* CompositionAttachmentData.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CompositionAttachmentData.swift; sourceTree = "<group>"; };
 		D626493623C0FD0000612E6E /* AllPhotosTableViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AllPhotosTableViewCell.swift; sourceTree = "<group>"; };
 		D626493723C0FD0000612E6E /* AllPhotosTableViewCell.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = AllPhotosTableViewCell.xib; sourceTree = "<group>"; };
@@ -1268,6 +1270,7 @@
 				D6DD2A44273D6C5700386A6C /* GIFImageView.swift */,
 				D641C77E213DC78A004B4513 /* InlineTextAttachment.swift */,
 				D620483323D3801D008A63EF /* LinkTextView.swift */,
+				D6262C9928D01C4B00390C1F /* LoadingTableViewCell.swift */,
 				D68E6F58253C9969001A1B4C /* MultiSourceEmojiLabel.swift */,
 				D627943A23A55BA600D38C68 /* NavigableTableViewCell.swift */,
 				D627943123A5466600D38C68 /* SelectableTableViewCell.swift */,
@@ -1918,6 +1921,7 @@
 				D6B8DB342182A59300424AF7 /* UIAlertController+Visibility.swift in Sources */,
 				D67C57AD21E265FC00C3118B /* LargeAccountDetailView.swift in Sources */,
 				D6114E1327F89B440080E273 /* TrendingLinkTableViewCell.swift in Sources */,
+				D6262C9A28D01C4B00390C1F /* LoadingTableViewCell.swift in Sources */,
 				D68C2AE325869BAB00548EFF /* AuxiliarySceneDelegate.swift in Sources */,
 				D6AEBB432321685E00E5038B /* OpenInSafariActivity.swift in Sources */,
 				D6C693FE2162FEEA007D6A6D /* UIViewController+Children.swift in Sources */,

Tusker/Screens/Notifications/NotificationsTableViewController.swift

@@ -9,7 +9,7 @@
 import UIKit
 import Pachyderm
 
-class NotificationsTableViewController: DiffableTimelineLikeTableViewController<NotificationsTableViewController.Section, NotificationGroup> {
+class NotificationsTableViewController: DiffableTimelineLikeTableViewController<NotificationsTableViewController.Section, NotificationsTableViewController.Item> {
 
     private let statusCell = "statusCell"
     private let actionGroupCell = "actionGroupCell"
@@ -56,7 +56,12 @@ class NotificationsTableViewController: DiffableTimelineLikeTableViewController<
     
     // MARK: - DiffableTimelineLikeTableViewController
     
-    override func cellProvider(_ tableView: UITableView, _ indexPath: IndexPath, _ group: NotificationGroup) -> UITableViewCell? {
+    override func cellProvider(_ tableView: UITableView, _ indexPath: IndexPath, _ item: Item) -> UITableViewCell? {
+        if case .loadingIndicator = item {
+            return self.loadingIndicatorCell(indexPath: indexPath)
+        }
+        let group = item.group!
+        
         switch group.kind {
         case .mention:
             guard let notification = group.notifications.first,
@@ -118,7 +123,7 @@ class NotificationsTableViewController: DiffableTimelineLikeTableViewController<
                 self.mastodonController.persistentContainer.addAll(notifications: notifications) {
                     var snapshot = Snapshot()
                     snapshot.appendSections([.notifications])
-                    snapshot.appendItems(groups, toSection: .notifications)
+                    snapshot.appendItems(groups.map { .notificationGroup($0) }, toSection: .notifications)
                     completion(.success(snapshot))
                 }
             }
@@ -145,11 +150,11 @@ class NotificationsTableViewController: DiffableTimelineLikeTableViewController<
                 let olderGroups = NotificationGroup.createGroups(notifications: newNotifications, only: self.groupTypes)
                 
                 self.mastodonController.persistentContainer.addAll(notifications: newNotifications) {
-                    let existingGroups = currentSnapshot().itemIdentifiers
+                    let existingGroups = currentSnapshot().itemIdentifiers.compactMap(\.group)
                     let merged = NotificationGroup.mergeGroups(first: existingGroups, second: olderGroups, only: self.groupTypes)
-                    var snapshot = NSDiffableDataSourceSnapshot<Section, NotificationGroup>()
+                    var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
                     snapshot.appendSections([.notifications])
-                    snapshot.appendItems(merged, toSection: .notifications)
+                    snapshot.appendItems(merged.map { .notificationGroup($0) }, toSection: .notifications)
                     completion(.success(snapshot))
                 }
             }
@@ -179,11 +184,11 @@ class NotificationsTableViewController: DiffableTimelineLikeTableViewController<
                 let newerGroups = NotificationGroup.createGroups(notifications: newNotifications, only: self.groupTypes)
                 
                 self.mastodonController.persistentContainer.addAll(notifications: newNotifications) {
-                    let existingGroups = currentSnapshot().itemIdentifiers
+                    let existingGroups = currentSnapshot().itemIdentifiers.compactMap(\.group)
                     let merged = NotificationGroup.mergeGroups(first: newerGroups, second: existingGroups, only: self.groupTypes)
-                    var snapshot = NSDiffableDataSourceSnapshot<Section, NotificationGroup>()
+                    var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
                     snapshot.appendSections([.notifications])
-                    snapshot.appendItems(merged, toSection: .notifications)
+                    snapshot.appendItems(merged.map { .notificationGroup($0) }, toSection: .notifications)
                     completion(.success(snapshot))
                 }
             }
@@ -191,9 +196,12 @@ class NotificationsTableViewController: DiffableTimelineLikeTableViewController<
     }
     
     private func dismissNotificationsInGroup(at indexPath: IndexPath, completion: (() -> Void)? = nil) {
-        guard let item = dataSource.itemIdentifier(for: indexPath) else { return }
+        guard let item = dataSource.itemIdentifier(for: indexPath),
+              let notifications = item.group?.notifications else {
+            return
+        }
         let group = DispatchGroup()
-        item.notifications
+        notifications
             .map { Pachyderm.Notification.dismiss(id: $0.id) }
             .forEach { (request) in
                 group.enter()
@@ -241,9 +249,23 @@ class NotificationsTableViewController: DiffableTimelineLikeTableViewController<
 }
 
 extension NotificationsTableViewController {
-    enum Section: CaseIterable, Hashable {
+    enum Section: DiffableTimelineLikeSection {
+        case loadingIndicator
         case notifications
     }
+    enum Item: DiffableTimelineLikeItem {
+        case loadingIndicator
+        case notificationGroup(NotificationGroup)
+        
+        var group: NotificationGroup? {
+            switch self {
+            case .loadingIndicator:
+                return nil
+            case .notificationGroup(let group):
+                return group
+            }
+        }
+    }
 }
 
 extension NotificationsTableViewController: TuskerNavigationDelegate {
@@ -265,7 +287,7 @@ extension NotificationsTableViewController: StatusTableViewCellDelegate {
 extension NotificationsTableViewController: UITableViewDataSourcePrefetching {
     func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
         for indexPath in indexPaths {
-            guard let group = dataSource.itemIdentifier(for: indexPath) else { continue }
+            guard let group = dataSource.itemIdentifier(for: indexPath)?.group else { continue }
             for notification in group.notifications {
                 guard let avatar = notification.account.avatar else { continue }
                 ImageCache.avatars.fetchIfNotCached(avatar)
@@ -275,7 +297,7 @@ extension NotificationsTableViewController: UITableViewDataSourcePrefetching {
     
     func tableView(_ tableView: UITableView, cancelPrefetchingForRowsAt indexPaths: [IndexPath]) {
         for indexPath in indexPaths {
-            guard let group = dataSource.itemIdentifier(for: indexPath) else { continue }
+            guard let group = dataSource.itemIdentifier(for: indexPath)?.group else { continue }
             for notification in group.notifications {
                 guard let avatar = notification.account.avatar else { continue }
                 ImageCache.avatars.cancelWithoutCallback(avatar)

Tusker/Screens/Profile/ProfileStatusesViewController.swift

@@ -60,15 +60,18 @@ class ProfileStatusesViewController: DiffableTimelineLikeTableViewController<Pro
     // MARK: - DiffableTimelineLikeTableViewController
     
     override func cellProvider(_ tableView: UITableView, _ indexPath: IndexPath, _ item: Item) -> UITableViewCell? {
+        switch item {
+        case .loadingIndicator:
+            return self.loadingIndicatorCell(indexPath: indexPath)
+            
+        case let .status(id: id, state: state, pinned: pinned):
             let cell = tableView.dequeueReusableCell(withIdentifier: "statusCell", for: indexPath) as! TimelineStatusTableViewCell
-        
             cell.delegate = self
-        // todo: dataSource.sectionIdentifier is only available on iOS 15
+            cell.showPinned = pinned
-        cell.showPinned = dataSource.snapshot().indexOfSection(.pinned) == indexPath.section
+            cell.updateUI(statusID: id, state: state)
-        cell.updateUI(statusID: item.id, state: item.state)
-        
             return cell
         }
+    }
     
     override func loadInitialItems(completion: @escaping (LoadResult) -> Void) {
         guard accountID != nil else {
@@ -94,7 +97,7 @@ class ProfileStatusesViewController: DiffableTimelineLikeTableViewController<Pro
                 self.mastodonController.persistentContainer.addAll(statuses: statuses) {
                     DispatchQueue.main.async {
                         var snapshot = self.dataSource.snapshot()
-                        snapshot.appendItems(statuses.map { Item(id: $0.id, state: .unknown, pinned: false) }, toSection: .statuses)
+                        snapshot.appendItems(statuses.map { .status(id: $0.id, state: .unknown, pinned: false) }, toSection: .statuses)
                         if self.kind == .statuses {
                             self.loadPinnedStatuses(snapshot: { snapshot }, completion: completion)
                         } else {
@@ -122,7 +125,7 @@ class ProfileStatusesViewController: DiffableTimelineLikeTableViewController<Pro
                     DispatchQueue.main.async {
                         var snapshot = snapshot()
                         snapshot.deleteItems(snapshot.itemIdentifiers(inSection: .pinned))
-                        snapshot.appendItems(statuses.map { Item(id: $0.id, state: .unknown, pinned: true) }, toSection: .pinned)
+                        snapshot.appendItems(statuses.map { .status(id: $0.id, state: .unknown, pinned: true) }, toSection: .pinned)
                         completion(.success(snapshot))
                     }
                 }
@@ -151,7 +154,7 @@ class ProfileStatusesViewController: DiffableTimelineLikeTableViewController<Pro
                 
                 self.mastodonController.persistentContainer.addAll(statuses: statuses) {
                     var snapshot = currentSnapshot()
-                    snapshot.appendItems(statuses.map { Item(id: $0.id, state: .unknown, pinned: false) }, toSection: .statuses)
+                    snapshot.appendItems(statuses.map { .status(id: $0.id, state: .unknown, pinned: false) }, toSection: .statuses)
                     completion(.success(snapshot))
                 }
             }
@@ -180,7 +183,7 @@ class ProfileStatusesViewController: DiffableTimelineLikeTableViewController<Pro
                 
                 self.mastodonController.persistentContainer.addAll(statuses: statuses) {
                     var snapshot = currentSnapshot()
-                    let items = statuses.map { Item(id: $0.id, state: .unknown, pinned: false) }
+                    let items = statuses.map { Item.status(id: $0.id, state: .unknown, pinned: false) }
                     if let first = snapshot.itemIdentifiers(inSection: .statuses).first {
                         snapshot.insertItems(items, beforeItem: first)
                     } else {
@@ -239,22 +242,22 @@ extension ProfileStatusesViewController {
 }
 
 extension ProfileStatusesViewController {
-    enum Section: CaseIterable {
+    enum Section: DiffableTimelineLikeSection {
+        case loadingIndicator
         case pinned
         case statuses
     }
-    struct Item: Hashable {
+    enum Item: DiffableTimelineLikeItem {
-        let id: String
+        case loadingIndicator
-        let state: StatusState
+        case status(id: String, state: StatusState, pinned: Bool)
-        let pinned: Bool
         
-        static func ==(lhs: Item, rhs: Item) -> Bool {
+        var id: String? {
-            return lhs.id == rhs.id && lhs.pinned == rhs.pinned
+            switch self {
+            case .loadingIndicator:
+                return nil
+            case .status(id: let id, state: _, pinned: _):
+                return id
             }
-        
-        func hash(into hasher: inout Hasher) {
-            hasher.combine(id)
-            hasher.combine(pinned)
         }
     }
 }

Tusker/Screens/Timeline/TimelineTableViewController.swift

@@ -97,6 +97,9 @@ class TimelineTableViewController: DiffableTimelineLikeTableViewController<Timel
 
     override func cellProvider(_ tableView: UITableView, _ indexPath: IndexPath, _ item: Item) -> UITableViewCell? {
         switch item {
+        case .loadingIndicator:
+            return self.loadingIndicatorCell(indexPath: indexPath)
+            
         case let .status(id: id, state: state):
             let cell = tableView.dequeueReusableCell(withIdentifier: "statusCell", for: indexPath) as! TimelineStatusTableViewCell
             
@@ -148,6 +151,9 @@ class TimelineTableViewController: DiffableTimelineLikeTableViewController<Timel
                 self.mastodonController.persistentContainer.addAll(statuses: statuses) {
                     DispatchQueue.main.async {
                         var snapshot = self.dataSource.snapshot()
+                        if snapshot.sectionIdentifiers.contains(.loadingIndicator) {
+                            snapshot.deleteSections([.loadingIndicator])
+                        }
                         snapshot.deleteSections([.statuses, .footer])
                         snapshot.appendSections([.statuses, .footer])
                         snapshot.appendItems(statuses.map { .status(id: $0.id, state: .unknown) }, toSection: .statuses)
@@ -245,12 +251,14 @@ class TimelineTableViewController: DiffableTimelineLikeTableViewController<Timel
 }
 
 extension TimelineTableViewController {
-    enum Section: Hashable, CaseIterable {
+    enum Section: DiffableTimelineLikeSection {
+        case loadingIndicator
         case header
         case statuses
         case footer
     }
-    enum Item: Hashable {
+    enum Item: DiffableTimelineLikeItem {
+        case loadingIndicator
         case status(id: String, state: StatusState)
         case confirmLoadMore
         case publicTimelineDescription(local: Bool)
@@ -270,13 +278,15 @@ extension TimelineTableViewController {
         
         func hash(into hasher: inout Hasher) {
             switch self {
-            case let .status(id: id, state: _):
+            case .loadingIndicator:
                 hasher.combine(0)
+            case let .status(id: id, state: _):
+                hasher.combine(1)
                 hasher.combine(id)
             case .confirmLoadMore:
-                hasher.combine(1)
-            case let .publicTimelineDescription(local: local):
                 hasher.combine(2)
+            case let .publicTimelineDescription(local: local):
+                hasher.combine(3)
                 hasher.combine(local)
             }
         }

Tusker/Screens/Utilities/DiffableTimelineLikeTableViewController.swift

@@ -9,7 +9,14 @@
 import UIKit
 import Pachyderm
 
-class DiffableTimelineLikeTableViewController<Section: Hashable & CaseIterable, Item: Hashable>: EnhancedTableViewController, RefreshableViewController {
+protocol DiffableTimelineLikeSection: Hashable, CaseIterable {
+    static var loadingIndicator: Self { get }
+}
+protocol DiffableTimelineLikeItem: Hashable {
+    static var loadingIndicator: Self { get }
+}
+
+class DiffableTimelineLikeTableViewController<Section: DiffableTimelineLikeSection, Item: DiffableTimelineLikeItem>: EnhancedTableViewController, RefreshableViewController {
     
     typealias Snapshot = NSDiffableDataSourceSnapshot<Section, Item>
     typealias LoadResult = Result<Snapshot, LoadError>
@@ -40,6 +47,7 @@ class DiffableTimelineLikeTableViewController<Section: Hashable & CaseIterable,
         
         tableView.rowHeight = UITableView.automaticDimension
         tableView.estimatedRowHeight = 140
+        tableView.register(LoadingTableViewCell.self, forCellReuseIdentifier: "loadingCell")
         
         #if !targetEnvironment(macCatalyst)
         self.refreshControl = UIRefreshControl()
@@ -104,15 +112,34 @@ class DiffableTimelineLikeTableViewController<Section: Hashable & CaseIterable,
         dataSource.apply(snapshot, animatingDifferences: false)
     }
     
+    private func showLoadingIndicatorDelayed() -> DispatchWorkItem {
+        let workItem = DispatchWorkItem { [weak self] in
+            guard let self = self else { return }
+            var snapshot = self.dataSource.snapshot()
+            snapshot.appendSections([.loadingIndicator])
+            snapshot.appendItems([.loadingIndicator])
+            self.dataSource.apply(snapshot, animatingDifferences: false)
+        }
+        DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(250), execute: workItem)
+        return workItem
+    }
+    
     private func loadInitial() {
         guard state == .unloaded else { return }
         // set loaded immediately so we don't trigger another request while the current one is running
         state = .loadingInitial
         
+        let showIndicator = showLoadingIndicatorDelayed()
+        
         loadInitialItems() { result in
             DispatchQueue.main.async {
+                showIndicator.cancel()
+                
                 switch result {
-                case let .success(snapshot):
+                case .success(var snapshot):
+                    if snapshot.sectionIdentifiers.contains(.loadingIndicator) {
+                        snapshot.deleteSections([.loadingIndicator])
+                    }
                     self.dataSource.apply(snapshot, animatingDifferences: false)
                     self.state = .loaded
                     
@@ -137,16 +164,22 @@ class DiffableTimelineLikeTableViewController<Section: Hashable & CaseIterable,
     }
     
     func loadOlder() {
-        guard state != .loadingOlder else { return }
+        guard state == .loaded else { return }
         
         state = .loadingOlder
         
+        let showIndicator = showLoadingIndicatorDelayed()
+        
         loadOlderItems(currentSnapshot: dataSource.snapshot) { result in
             DispatchQueue.main.async {
                 self.state = .loaded
+                showIndicator.cancel()
 
                 switch result {
-                case let .success(snapshot):
+                case .success(var snapshot):
+                    if snapshot.sectionIdentifiers.contains(.loadingIndicator) {
+                        snapshot.deleteSections([.loadingIndicator])
+                    }
                     self.dataSource.apply(snapshot, animatingDifferences: false)
 
                 case let .failure(.client(error)):
@@ -263,6 +296,12 @@ class DiffableTimelineLikeTableViewController<Section: Hashable & CaseIterable,
     
     // MARK: - Subclass Methods
     
+    func loadingIndicatorCell(indexPath: IndexPath) -> UITableViewCell? {
+        let cell = tableView.dequeueReusableCell(withIdentifier: "loadingCell", for: indexPath) as! LoadingTableViewCell
+        cell.indicator.startAnimating()
+        return cell
+    }
+    
     func cellProvider(_ tableView: UITableView, _ indexPath: IndexPath, _ item: Item) -> UITableViewCell? {
         fatalError("cellProvider(_:_:_:) must be implemented by subclasses")
     }

Tusker/Views/LoadingTableViewCell.swift

@@ -0,0 +1,29 @@
+//
+//  LoadingTableViewCell.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 9/12/22.
+//  Copyright © 2022 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+class LoadingTableViewCell: UITableViewCell {
+    let indicator = UIActivityIndicatorView(style: .medium)
+    
+    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
+        super.init(style: style, reuseIdentifier: reuseIdentifier)
+        
+        indicator.translatesAutoresizingMaskIntoConstraints = false
+        contentView.addSubview(indicator)
+        NSLayoutConstraint.activate([
+            indicator.centerXAnchor.constraint(equalTo: centerXAnchor),
+            indicator.topAnchor.constraint(equalTo: topAnchor),
+            indicator.bottomAnchor.constraint(equalTo: bottomAnchor),
+        ])
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+}