Remove notifications from the bottom when scrolling up notifications list

Tusker/Screens/Notifications/NotificationsTableViewController.swift

@@ -127,6 +127,33 @@ class NotificationsTableViewController: EnhancedTableViewController {
     // MARK: - Table view delegate
 
     override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
+        // 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 }
             

Tusker/Screens/Timeline/TimelineTableViewController.swift

@@ -19,9 +19,6 @@ class TimelineTableViewController: EnhancedTableViewController {
     var newer: RequestRange?
     var older: RequestRange?
     
-    private var prevScrollViewContentOffset: CGPoint?
-    private var scrollViewDirection: CGFloat = 0
-    
     init(for timeline: Timeline, mastodonController: MastodonController) {
         self.timeline = timeline
         self.mastodonController = mastodonController
@@ -143,7 +140,7 @@ class TimelineTableViewController: EnhancedTableViewController {
                     for (id, _) in statusesToRemove {
                         mastodonController.persistentContainer.status(for: id)?.decrementReferenceCount()
                     }
-                    timelineSegments[timelineSegments.count - 1].removeLast(20)
+                    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
@@ -197,6 +194,8 @@ class TimelineTableViewController: EnhancedTableViewController {
         return (tableView.cellForRow(at: indexPath) as? TableViewSwipeActionProvider)?.trailingSwipeActionsConfiguration()
     }
     
+    // MARK: Interaction
+    
     @objc func refreshStatuses(_ sender: Any) {
         guard let newer = newer else { return }
         
@@ -228,15 +227,6 @@ class TimelineTableViewController: EnhancedTableViewController {
         }
     }
 
-    // Mark: Scroll View Delegate
-    override func scrollViewDidScroll(_ scrollView: UIScrollView) {
-        if let prev = prevScrollViewContentOffset {
-            scrollViewDirection = scrollView.contentOffset.y - prev.y
-        }
-        prevScrollViewContentOffset = scrollView.contentOffset
-    }
-    
-
     @objc func composePressed(_ sender: Any) {
         compose()
     }

Tusker/Screens/Utilities/EnhancedTableViewController.swift

@@ -13,6 +13,10 @@ class EnhancedTableViewController: UITableViewController {
 
     private var prevScrollToTopOffset: CGPoint? = nil
     private(set) var isCurrentlyScrollingToTop = false
+    private var prevScrollViewContentOffset: CGPoint?
+    private(set) var scrollViewDirection: CGFloat = 0
+    
+    // MARK: Scroll View Delegate
 
     override func scrollViewShouldScrollToTop(_ scrollView: UIScrollView) -> Bool {
         if let offset = prevScrollToTopOffset {
@@ -37,6 +41,14 @@ class EnhancedTableViewController: UITableViewController {
         prevScrollToTopOffset = nil
     }
     
+    override func scrollViewDidScroll(_ scrollView: UIScrollView) {
+        if let prev = prevScrollViewContentOffset {
+            scrollViewDirection = scrollView.contentOffset.y - prev.y
+        }
+        prevScrollViewContentOffset = scrollView.contentOffset
+    }
+    
+    // MARK: Table View Delegate
 
     override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
         if let cell = tableView.cellForRow(at: indexPath) as? SelectableTableViewCell {