Tusker.xcodeproj/project.pbxproj

@@ -145,7 +145,6 @@
 		D6531DEE246B81C9000F9538 /* GifvAttachmentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6531DED246B81C9000F9538 /* GifvAttachmentView.swift */; };
 		D6531DF0246B867E000F9538 /* GifvAttachmentViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6531DEF246B867E000F9538 /* GifvAttachmentViewController.swift */; };
 		D6538945214D6D7500E3CEFC /* TableViewSwipeActionProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6538944214D6D7500E3CEFC /* TableViewSwipeActionProvider.swift */; };
-		D65C6BF525478A9C00A6E89C /* BackgroundableViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D65C6BF425478A9C00A6E89C /* BackgroundableViewController.swift */; };
 		D65F613423AEAB6600F3CFD3 /* OnboardingTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D65F613323AEAB6600F3CFD3 /* OnboardingTests.swift */; };
 		D6620ACE2511A0ED00312CA0 /* StatusStateResolver.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6620ACD2511A0ED00312CA0 /* StatusStateResolver.swift */; };
 		D663625D2135C74800C9CBA2 /* ConversationMainStatusTableViewCell.xib in Resources */ = {isa = PBXBuildFile; fileRef = D663625C2135C74800C9CBA2 /* ConversationMainStatusTableViewCell.xib */; };
@@ -483,7 +482,6 @@
 		D6531DED246B81C9000F9538 /* GifvAttachmentView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GifvAttachmentView.swift; sourceTree = "<group>"; };
 		D6531DEF246B867E000F9538 /* GifvAttachmentViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GifvAttachmentViewController.swift; sourceTree = "<group>"; };
 		D6538944214D6D7500E3CEFC /* TableViewSwipeActionProvider.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TableViewSwipeActionProvider.swift; sourceTree = "<group>"; };
-		D65C6BF425478A9C00A6E89C /* BackgroundableViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BackgroundableViewController.swift; sourceTree = "<group>"; };
 		D65F612D23AE990C00F3CFD3 /* Embassy.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = Embassy.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		D65F613023AE99E000F3CFD3 /* Ambassador.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; path = Ambassador.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		D65F613323AEAB6600F3CFD3 /* OnboardingTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OnboardingTests.swift; sourceTree = "<group>"; };
@@ -1329,7 +1327,6 @@
 				D693DE5823FE24300061E07D /* InteractivePushTransition.swift */,
 				D6DFC69D242C490400ACC392 /* TrackpadScrollGestureRecognizer.swift */,
 				D6412B0224AFF6A600F5412E /* TabBarScrollableViewController.swift */,
-				D65C6BF425478A9C00A6E89C /* BackgroundableViewController.swift */,
 			);
 			path = Utilities;
 			sourceTree = "<group>";
@@ -1867,7 +1864,6 @@
 				D6BC9DDA232D8BE5002CA326 /* SearchResultsViewController.swift in Sources */,
 				D627FF7F217E95E000CC0648 /* DraftTableViewCell.swift in Sources */,
 				D6DF95C12533F5DE0027A9B6 /* RelationshipMO.swift in Sources */,
-				D65C6BF525478A9C00A6E89C /* BackgroundableViewController.swift in Sources */,
 				D6AEBB4A23216F0400E5038B /* UnfollowAccountActivity.swift in Sources */,
 				D663626421360D2300C9CBA2 /* AvatarStyle.swift in Sources */,
 				D6D3FDE024F41B8400FF50A5 /* ComposeContainerView.swift in Sources */,

Tusker/SceneDelegate.swift

@@ -108,10 +108,6 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
         // Use this method to save data, release shared resources, and store enough scene-specific state information
         // to restore the scene back to its current state.
         
-        if let rootVC = window?.rootViewController as? BackgroundableViewController {
-            rootVC.sceneDidEnterBackground()
-        }
-        
         try! scene.session.mastodonController?.persistentContainer.viewContext.save()
     }
     

Tusker/Screens/Main/MainSplitViewController.swift

@@ -334,32 +334,4 @@ extension MainSplitViewController: TuskerRootViewController {
             }
         }
     }
-    
-    func getTabController(tab: MainTabBarViewController.Tab) -> UIViewController? {
-        if traitCollection.horizontalSizeClass == .compact {
-            return tabBarViewController?.getTabController(tab: tab)
-        } else {
-            if tab == .compose {
-                return nil
-            } else if case .tab(tab) = sidebar.selectedItem {
-                return viewController(for: .secondary)
-            } else {
-                return nil
-            }
-        }
-    }
-}
-
-@available(iOS 14.0, *)
-extension MainSplitViewController: BackgroundableViewController {
-    func sceneDidEnterBackground() {
-        if traitCollection.horizontalSizeClass == .compact {
-            tabBarViewController.sceneDidEnterBackground()
-        } else {
-            // todo: should this do the same for the sidebar VC as well?
-            if let contentVC = viewController(for: .secondary) as? BackgroundableViewController {
-                contentVC.sceneDidEnterBackground()
-            }
-        }
-    }
 }

Tusker/Screens/Main/MainTabBarViewController.swift

@@ -136,11 +136,3 @@ extension MainTabBarViewController: TuskerRootViewController {
         }
     }
 }
-
-extension MainTabBarViewController: BackgroundableViewController {
-    func sceneDidEnterBackground() {
-        if let selectedVC = selectedViewController as? BackgroundableViewController {
-            selectedVC.sceneDidEnterBackground()
-        }
-    }
-}

Tusker/Screens/Main/TuskerRootViewController.swift

@@ -11,5 +11,4 @@ import UIKit
 protocol TuskerRootViewController: UIViewController {
     func presentCompose()
     func select(tab: MainTabBarViewController.Tab)
-    func getTabController(tab: MainTabBarViewController.Tab) -> UIViewController?
 }

Tusker/Screens/Notifications/NotificationsTableViewController.swift

@@ -19,18 +19,15 @@ class NotificationsTableViewController: EnhancedTableViewController {
     
     weak var mastodonController: MastodonController!
     
-    private let excludedTypes: [Pachyderm.Notification.Kind]
-    private let groupTypes = [Notification.Kind.favourite, .reblog, .follow]
+    let excludedTypes: [Pachyderm.Notification.Kind]
+    let groupTypes = [Notification.Kind.favourite, .reblog, .follow]
     
     private var loaded = false
 
-    private var groups: [NotificationGroup] = []
+    var groups: [NotificationGroup] = []
     
-    private let pageSize = 20
-    private var newer: RequestRange?
-    private var older: RequestRange?
-    
-    private var lastLastVisibleRow: IndexPath?
+    var newer: RequestRange?
+    var older: RequestRange?
     
     init(allowedTypes: [Pachyderm.Notification.Kind], mastodonController: MastodonController) {
         self.excludedTypes = Array(Set(Pachyderm.Notification.Kind.allCases).subtracting(allowedTypes))
@@ -87,41 +84,6 @@ class NotificationsTableViewController: EnhancedTableViewController {
         }
     }
     
-    override func viewWillDisappear(_ animated: Bool) {
-        super.viewWillDisappear(animated)
-        
-        pruneOffscreenRows()
-    }
-    
-    private func pruneOffscreenRows() {
-        guard let lastVisibleRow = lastLastVisibleRow else {
-            return
-        }
-        let lastRowIndex = groups.count - 1
-        
-        if lastVisibleRow.row < lastRowIndex - pageSize {
-            // if there are more than 20 rows below the lats visible one
-            
-            let rowIndicesToRemove = (lastVisibleRow.row + pageSize)..<groups.count
-            
-            let groupsToRemove = groups[rowIndicesToRemove]
-            for group in groupsToRemove {
-                for notification in group.notifications {
-                    if let id = notification.status?.id {
-                        mastodonController.persistentContainer.status(for: id)?.decrementReferenceCount()
-                    }
-                }
-            }
-            
-            groups.removeSubrange(rowIndicesToRemove)
-            
-            let removedIndexPaths = rowIndicesToRemove.map { IndexPath(row: $0, section: 0) }
-            UIView.performWithoutAnimation {
-                tableView.deleteRows(at: removedIndexPaths, with: .none)
-            }
-        }
-    }
-    
     // MARK: - Table view data source
 
     override func numberOfSections(in tableView: UITableView) -> Int {
@@ -175,7 +137,32 @@ class NotificationsTableViewController: EnhancedTableViewController {
     // MARK: - Table view delegate
 
     override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
-        lastLastVisibleRow = tableView.indexPathsForVisibleRows?.last
+        // see TimelineTableViewController.tableView(_:willDisplay:forRowAt:)
+        if !isCurrentlyScrollingToTop, scrollViewDirection < 0 {
+            let pageSize = 20
+            if groups.count > 2 * pageSize,
+                indexPath.row < groups.count - (2 * pageSize) {
+                let groupsToRemove = groups[groups.count - pageSize..<groups.count]
+                for group in groupsToRemove {
+                    for notification in group.notifications {
+                        // todo: reference count accounts
+//                        mastodonController.persistentContainer.account(for: notification.account.id)?.decrementReferenceCount()
+                        if let id = notification.status?.id {
+                            mastodonController.persistentContainer.status(for: id)?.decrementReferenceCount()
+                        }
+                    }
+                }
+                let removedIndexPaths = (groups.count - 20..<groups.count).map { IndexPath(row: $0, section: 0) }
+                
+                groups.removeLast(pageSize)
+                
+                DispatchQueue.main.async {
+                    UIView.performWithoutAnimation {
+                        tableView.deleteRows(at: removedIndexPaths, with: .none)
+                    }
+                }
+            }
+        }
         
         if indexPath.row == groups.count - 1 {
             guard let older = older else { return }
@@ -318,9 +305,3 @@ extension NotificationsTableViewController: UITableViewDataSourcePrefetching {
         }
     }
 }
-
-extension NotificationsTableViewController: BackgroundableViewController {
-    func sceneDidEnterBackground() {
-        pruneOffscreenRows()
-    }
-}

Tusker/Screens/Profile/ProfileStatusesViewController.swift

@@ -224,6 +224,8 @@ class ProfileStatusesViewController: EnhancedTableViewController {
     }
     
     override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
+        // todo: if scrolling up, remove statuses at bottom like timeline VC
+        
         // load older statuses if at bottom
         if timelineSegments.count > 0,
            indexPath.section == timelineSegments.count,

Tusker/Screens/Timeline/TimelineTableViewController.swift

@@ -18,11 +18,8 @@ class TimelineTableViewController: EnhancedTableViewController, StatusTableViewC
     
     var timelineSegments: [[(id: String, state: StatusState)]] = []
     
-    private let pageSize = 20
-    private var newer: RequestRange?
-    private var older: RequestRange?
-    
-    private var lastLastVisibleRow: IndexPath?
+    var newer: RequestRange?
+    var older: RequestRange?
     
     init(for timeline: Timeline, mastodonController: MastodonController) {
         self.timeline = timeline
@@ -76,12 +73,6 @@ class TimelineTableViewController: EnhancedTableViewController, StatusTableViewC
         loadInitialStatuses()
     }
     
-    override func viewWillDisappear(_ animated: Bool) {
-        super.viewWillDisappear(animated)
-        
-        pruneOffscreenRows()
-    }
-    
     func loadInitialStatuses() {
         guard !loaded else { return }
         loaded = true
@@ -101,52 +92,6 @@ class TimelineTableViewController: EnhancedTableViewController, StatusTableViewC
         }
     }
 
-    private func pruneOffscreenRows() {
-        guard let lastVisibleRow = lastLastVisibleRow else {
-            return
-        }
-        let lastSectionIndex = timelineSegments.count - 1
-        
-        if lastVisibleRow.section < lastSectionIndex {
-            // if there is a section below the last visible one
-            
-            let sectionsToRemove = (lastVisibleRow.section + 1)...lastSectionIndex
-            
-            for section in sectionsToRemove {
-                for (id, _) in timelineSegments.remove(at: section) {
-                    mastodonController.persistentContainer.status(for: id)?.decrementReferenceCount()
-                }
-            }
-            
-            UIView.performWithoutAnimation {
-                tableView.deleteSections(IndexSet(sectionsToRemove), with: .none)
-            }
-            
-        } else if lastVisibleRow.section == lastSectionIndex {
-            let lastSection = timelineSegments.last!
-            let lastRowIndex = lastSection.count - 1
-            
-            if lastVisibleRow.row < lastRowIndex - 20 {
-                // if there are more than 20 rows in the current section below the last visible one
-                
-                let rowIndicesInLastSectionToRemove = (lastVisibleRow.row + 20)..<lastSection.count
-                
-                let statusesToRemove = lastSection[rowIndicesInLastSectionToRemove]
-                for (id, _) in statusesToRemove {
-                    mastodonController.persistentContainer.status(for: id)?.decrementReferenceCount()
-                }
-                
-                timelineSegments[lastSectionIndex].removeSubrange(rowIndicesInLastSectionToRemove)
-
-                let removedIndexPaths = rowIndicesInLastSectionToRemove.map { IndexPath(row: $0, section: lastSectionIndex) }
-                UIView.performWithoutAnimation {
-                    tableView.deleteRows(at: removedIndexPaths, with: .none)
-                }
-
-            }
-        }
-    }
-
     // MARK: - Table view data source
 
     override func numberOfSections(in tableView: UITableView) -> Int {
@@ -172,8 +117,58 @@ class TimelineTableViewController: EnhancedTableViewController, StatusTableViewC
     // MARK: - Table view delegate
     
     override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
-        // this assumes that indexPathsForVisibleRows is always in order
-        lastLastVisibleRow = tableView.indexPathsForVisibleRows?.last
+        // don't remove rows when jumping to the top, otherwise jumping back down might try to show removed rows
+        // when scrolling upwards, decrement reference counts for old statuses, if necessary
+        if !isCurrentlyScrollingToTop, scrollViewDirection < 0 {
+            if indexPath.section <= timelineSegments.count - 2 {
+                // decrement ref counts for all sections below the section below the current section
+                // (e.g., there exist sections 0, 1, 2 and we're currently scrolling upwards in section 0, we want to remove section 2)
+                
+                // todo: this is in the hot path for scrolling, possibly move this to a background thread?
+                let sectionsToRemove = indexPath.section + 1..<timelineSegments.count
+                for section in sectionsToRemove {
+                    for (id, _) in timelineSegments.remove(at: section) {
+                        mastodonController.persistentContainer.status(for: id)?.decrementReferenceCount()
+                    }
+                }
+                // see below comment about DispatchQueue.main.async
+                DispatchQueue.main.async {
+                    UIView.performWithoutAnimation {
+                        tableView.deleteSections(IndexSet(sectionsToRemove), with: .none)
+                    }
+                }
+            } else {
+                // we are scrolling in the last or second to last section
+                // grab the last section and, if there is more than one page in the last section
+                // (we never want to remove the only page in the last section unless there is another section between it and the user),
+                // remove the last page and decrement reference counts
+                let pageSize = 20 // todo: this should come from somewhere in Pachyderm
+                let lastSection = timelineSegments.last!
+                if lastSection.count > 2 * pageSize,
+                    indexPath.row < lastSection.count - (2 * pageSize) {
+                    // todo: this is in the hot path for scrolling, possibly move this to a background thread?
+                    let statusesToRemove = lastSection[lastSection.count - pageSize..<lastSection.count]
+                    for (id, _) in statusesToRemove {
+                        mastodonController.persistentContainer.status(for: id)?.decrementReferenceCount()
+                    }
+                    timelineSegments[timelineSegments.count - 1].removeLast(pageSize)
+                    
+                    let removedIndexPaths = (lastSection.count - 20..<lastSection.count).map { IndexPath(row: $0, section: timelineSegments.count - 1) }
+                    // Removing this DispatchQueue.main.async call causes things to break when scrolling
+                    // back down towards the removed rows. There would be a index out of bounds crash
+                    // because, while we've already removed the statuses from our model, the table view doesn't seem to know that.
+                    // It seems like tableView update calls made from inside tableView(_:willDisplay:forRowAt:) are silently ignored.
+                    // Calling tableView.numberOfRows(inSection: 0) when trapped in the debugger after the aforementioned IOOB
+                    // will produce an incorrect value (it will be some multiple of pageSize too high).
+                    // Deferring the tableView update until the next runloop iteration seems to solve that.
+                    DispatchQueue.main.async {
+                        UIView.performWithoutAnimation {
+                            tableView.deleteRows(at: removedIndexPaths, with: .none)
+                        }
+                    }
+                }
+            }
+        }
         
         // load older statuses, if necessary
         if indexPath.section == timelineSegments.count - 1,
@@ -287,9 +282,3 @@ extension TimelineTableViewController: UITableViewDataSourcePrefetching {
         }
     }
 }
-
-extension TimelineTableViewController: BackgroundableViewController {
-    func sceneDidEnterBackground() {
-        pruneOffscreenRows()
-    }
-}

Tusker/Screens/Utilities/BackgroundableViewController.swift

@@ -1,13 +0,0 @@
-//
-//  BackgroundableViewController.swift
-//  Tusker
-//
-//  Created by Shadowfacts on 10/26/20.
-//  Copyright © 2020 Shadowfacts. All rights reserved.
-//
-
-import Foundation
-
-protocol BackgroundableViewController {
-    func sceneDidEnterBackground()
-}

Tusker/Screens/Utilities/EnhancedNavigationViewController.swift

@@ -74,11 +74,3 @@ class EnhancedNavigationViewController: UINavigationController {
     }
 
 }
-
-extension EnhancedNavigationViewController: BackgroundableViewController {
-    func sceneDidEnterBackground() {
-        if let topVC = topViewController as? BackgroundableViewController {
-            topVC.sceneDidEnterBackground()
-        }
-    }
-}

Tusker/Screens/Utilities/SegmentedPageViewController.swift

@@ -71,11 +71,3 @@ extension SegmentedPageViewController: TabBarScrollableViewController {
         }
     }
 }
-
-extension SegmentedPageViewController: BackgroundableViewController {
-    func sceneDidEnterBackground() {
-        if let current = pageControllers[currentIndex] as? BackgroundableViewController {
-            current.sceneDidEnterBackground()
-        }
-    }
-}

Tusker/Shortcuts/UserActivityManager.swift

@@ -21,14 +21,14 @@ class UserActivityManager {
         return scene.session.mastodonController!
     }
     
-    private static func getMainViewController() -> TuskerRootViewController {
+    private static func getMainTabBarController() -> MainTabBarViewController {
         let scene = UIApplication.shared.connectedScenes.compactMap { $0 as? UIWindowScene }.first!
         let window = scene.windows.first { $0.isKeyWindow }!
-        return window.rootViewController as! TuskerRootViewController
+        return window.rootViewController as! MainTabBarViewController
     }
     
     private static func present(_ vc: UIViewController, animated: Bool = true) {
-        getMainViewController().present(vc, animated: animated)
+        getMainTabBarController().present(vc, animated: animated)
     }
 
     // MARK: - New Post
@@ -66,9 +66,9 @@ class UserActivityManager {
     }
     
     static func handleCheckNotifications(activity: NSUserActivity) {
-        let mainViewController = getMainViewController()
-        mainViewController.select(tab: .notifications)
-        if let navigationController = mainViewController.getTabController(tab: .notifications) as? UINavigationController,
+        let tabBarController = getMainTabBarController()
+        tabBarController.select(tab: .notifications)
+        if let navigationController = tabBarController.getTabController(tab: .notifications) as? UINavigationController,
             let notificationsPageController = navigationController.viewControllers.first as? NotificationsPageViewController {
             navigationController.popToRootViewController(animated: false)
             notificationsPageController.loadViewIfNeeded()
@@ -86,9 +86,9 @@ class UserActivityManager {
     }
     
     static func handleCheckMentions(activity: NSUserActivity) {
-        let mainViewController = getMainViewController()
-        mainViewController.select(tab: .notifications)
-        if let navController = mainViewController.getTabController(tab: .notifications) as? UINavigationController,
+        let tabBarController = getMainTabBarController()
+        tabBarController.select(tab: .notifications)
+        if let navController = tabBarController.getTabController(tab: .notifications) as? UINavigationController,
             let notificationsPageController = navController.viewControllers.first as? NotificationsPageViewController {
             navController.popToRootViewController(animated: false)
             notificationsPageController.loadViewIfNeeded()
@@ -133,12 +133,9 @@ class UserActivityManager {
                 return
         }
         
-        let mainViewController = getMainViewController()
-        mainViewController.select(tab: .timelines)
-        guard let navigationController = mainViewController.getTabController(tab: .timelines) as? UINavigationController else {
-            return
-        }
-        
+        let tabBarController = getMainTabBarController()
+        tabBarController.select(tab: .timelines)
+        let navigationController = tabBarController.viewControllers![0] as! UINavigationController
         switch timeline {
         case .home, .public(true), .public(false):
             navigationController.popToRootViewController(animated: false)
@@ -173,9 +170,9 @@ class UserActivityManager {
     }
     
     static func handleSearch(activity: NSUserActivity) {
-        let mainViewController = getMainViewController()
-        mainViewController.select(tab: .explore)
-        if let navigationController = mainViewController.getTabController(tab: .explore) as? UINavigationController,
+        let tabBarController = getMainTabBarController()
+        tabBarController.select(tab: .explore)
+        if let navigationController = tabBarController.getTabController(tab: .explore) as? UINavigationController,
             let exploreController = navigationController.viewControllers.first as? ExploreViewController {
             navigationController.popToRootViewController(animated: false)
             exploreController.searchController.isActive = true
@@ -192,9 +189,9 @@ class UserActivityManager {
     }
     
     static func handleBookmarks(activity: NSUserActivity) {
-        let mainViewController = getMainViewController()
-        mainViewController.select(tab: .explore)
-        if let navigationController = mainViewController.getTabController(tab: .explore) as? UINavigationController {
+        let tabBarController = getMainTabBarController()
+        tabBarController.select(tab: .explore)
+        if let navigationController = tabBarController.getTabController(tab: .explore) as? UINavigationController {
             navigationController.popToRootViewController(animated: false)
             navigationController.pushViewController(BookmarksTableViewController(mastodonController: mastodonController), animated: false)
         }