Prune offscreen rows on new timeline

Closes #182

Tusker/CoreData/MastodonCachePersistentStore.swift

@@ -10,6 +10,9 @@ import Foundation
 import CoreData
 import Pachyderm
 import Combine
+import OSLog
+
+fileprivate let logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "PersistentStore")
 
 class MastodonCachePersistentStore: NSPersistentContainer {
     
@@ -49,7 +52,8 @@ class MastodonCachePersistentStore: NSPersistentContainer {
         
         loadPersistentStores { (description, error) in
             if let error = error {
-                fatalError("Unable to load persistent store: \(error)")
+                logger.error("Unable to load persistent store: \(String(describing: error), privacy: .public)")
+                fatalError("Unable to load persistent store")
             }
         }
         
@@ -58,6 +62,18 @@ class MastodonCachePersistentStore: NSPersistentContainer {
         NotificationCenter.default.addObserver(self, selector: #selector(managedObjectsDidChange), name: .NSManagedObjectContextObjectsDidChange, object: viewContext)
     }
     
+    func save(context: NSManagedObjectContext) {
+        guard context.hasChanges else {
+            return
+        }
+        do {
+            try context.save()
+        } catch {
+            logger.error("Unable to save managed object context: \(String(describing: error), privacy: .public)")
+            fatalError("Unable to save managed object context")
+        }
+    }
+    
     func status(for id: String, in context: NSManagedObjectContext? = nil) -> StatusMO? {
         let context = context ?? viewContext
         let request: NSFetchRequest<StatusMO> = StatusMO.fetchRequest()
@@ -84,9 +100,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
         let context = context ?? backgroundContext
         context.perform {
             let statusMO = self.upsert(status: status, context: context)
-            if context.hasChanges {
-                try! context.save()
-            }
+            self.save(context: context)
             completion?(statusMO)
             self.statusSubject.send(status.id)
         }
@@ -95,9 +109,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
     @MainActor
     func addOrUpdateOnViewContext(status: Status) -> StatusMO {
         let statusMO = self.upsert(status: status, context: viewContext)
-        if viewContext.hasChanges {
-            try! viewContext.save()
-        }
+        self.save(context: viewContext)
         statusSubject.send(status.id)
         return statusMO
     }
@@ -105,9 +117,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
     func addAll(statuses: [Status], completion: (() -> Void)? = nil) {
         backgroundContext.perform {
             statuses.forEach { self.upsert(status: $0, context: self.backgroundContext) }
-            if self.backgroundContext.hasChanges {
-                try! self.backgroundContext.save()
-            }
+            self.save(context: self.backgroundContext)
             statuses.forEach { self.statusSubject.send($0.id) }
             completion?()
         }
@@ -146,9 +156,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
     func addOrUpdate(account: Account, completion: ((AccountMO) -> Void)? = nil) {
         backgroundContext.perform {
             let accountMO = self.upsert(account: account)
-            if self.backgroundContext.hasChanges {
-                try! self.backgroundContext.save()
-            }
+            self.save(context: self.backgroundContext)
             completion?(accountMO)
             self.accountSubject.send(account.id)
         }
@@ -180,9 +188,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
     func addOrUpdate(relationship: Relationship, completion: ((RelationshipMO) -> Void)? = nil) {
         backgroundContext.perform {
             let relationshipMO = self.upsert(relationship: relationship)
-            if self.backgroundContext.hasChanges {
-                try! self.backgroundContext.save()
-            }
+            self.save(context: self.backgroundContext)
             completion?(relationshipMO)
             self.relationshipSubject.send(relationship.id)
         }
@@ -191,9 +197,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
     func addAll(accounts: [Account], completion: (() -> Void)? = nil) {
         backgroundContext.perform {
             accounts.forEach { self.upsert(account: $0) }
-            if self.backgroundContext.hasChanges {
-                try! self.backgroundContext.save()
-            }
+            self.save(context: self.backgroundContext)
             completion?()
             accounts.forEach { self.accountSubject.send($0.id) }
         }
@@ -207,9 +211,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
             let accounts = notifications.filter { $0.kind != .mention }.map { $0.account }
             statuses.forEach { self.upsert(status: $0, context: self.backgroundContext) }
             accounts.forEach { self.upsert(account: $0) }
-            if self.backgroundContext.hasChanges {
-                try! self.backgroundContext.save()
-            }
+            self.save(context: self.backgroundContext)
             completion?()
             statuses.forEach { self.statusSubject.send($0.id) }
             accounts.forEach { self.accountSubject.send($0.id) }
@@ -232,9 +234,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
             updatedAccounts.forEach(self.accountSubject.send)
             updatedStatuses.forEach(self.statusSubject.send)
             
-            if self.backgroundContext.hasChanges {
-                try! self.backgroundContext.save()
-            }
+            self.save(context: self.backgroundContext)
             completion?()
         }
     }

Tusker/Info.plist

@@ -4,7 +4,7 @@
 <dict>
 	<key>OSLogPreferences</key>
 	<dict>
-		<key>$(PRODUCT_BUNDLE_IDENTIFIER)</key>
+		<key>space.vaccor.Tusker</key>
 		<dict>
 			<key>DEFAULT-OPTIONS</key>
 			<dict>

Tusker/Screens/Timeline/HashtagTimelineViewController.swift

@@ -58,7 +58,7 @@ class HashtagTimelineViewController: TimelineTableViewController {
         } else {
             _ = SavedHashtag(hashtag: hashtag, context: context)
         }
-        try! context.save()
+        mastodonController.persistentContainer.save(context: context)
     }
 
 }

Tusker/Screens/Timeline/InstanceTimelineViewController.swift

@@ -94,7 +94,7 @@ class InstanceTimelineViewController: TimelineTableViewController {
             _ = SavedInstance(url: instanceURL, context: context)
             delegate?.didSaveInstance(url: instanceURL)
         }
-        try? context.save()
+        mastodonController.persistentContainer.save(context: context)
     }
 
 }

Tusker/Screens/Timeline/TimelineViewController.swift

@@ -124,7 +124,7 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
     private func applyInitialSnapshot() {
         if case .public(let local) = timeline,
            (local && !Preferences.shared.hasShownLocalTimelineDescription) ||
-            (!local && Preferences.shared.hasShownFederatedTimelineDescription) {
+            (!local && !Preferences.shared.hasShownFederatedTimelineDescription) {
             var snapshot = dataSource.snapshot()
             snapshot.appendSections([.header])
             snapshot.appendItems([.publicTimelineDescription], toSection: .header)
@@ -144,6 +144,25 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
         }
     }
     
+    override func viewDidAppear(_ animated: Bool) {
+        super.viewDidAppear(animated)
+        
+        if isShowingTimelineDescription,
+           case .public(let local) = timeline {
+            if local {
+                Preferences.shared.hasShownLocalTimelineDescription = true
+            } else {
+                Preferences.shared.hasShownFederatedTimelineDescription = true
+            }
+        }
+    }
+    
+    override func viewDidDisappear(_ animated: Bool) {
+        super.viewDidDisappear(animated)
+        
+        pruneOffscreenRows()
+    }
+    
     private func removeTimelineDescriptionCell() {
         var snapshot = dataSource.snapshot()
         snapshot.deleteSections([.header])
@@ -151,6 +170,25 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
         isShowingTimelineDescription = false
     }
     
+    private func pruneOffscreenRows() {
+        guard let lastVisibleIndexPath = collectionView.indexPathsForVisibleItems.last else {
+            return
+        }
+        var snapshot = dataSource.snapshot()
+        let items = snapshot.itemIdentifiers(inSection: .statuses)
+        let pageSize = 20
+        let numberOfPagesToPrune = (items.count - lastVisibleIndexPath.row - 1) / pageSize
+        if numberOfPagesToPrune > 0 {
+            let itemsToRemove = Array(items.suffix(numberOfPagesToPrune * pageSize))
+            snapshot.deleteItems(itemsToRemove)
+        }
+        dataSource.apply(snapshot, animatingDifferences: false)
+        
+        if case .status(id: let id, state: _) = snapshot.itemIdentifiers(inSection: .statuses).last {
+            older = .before(id: id, count: nil)
+        }
+    }
+    
     @objc func refresh() {
         Task {
             await controller.loadNewer()

Tusker/Screens/Utilities/Previewing.swift

@@ -110,7 +110,7 @@ extension MenuActionProvider {
                     } else {
                         _ = SavedHashtag(hashtag: hashtag, context: context)
                     }
-                    try! context.save()
+                    mastodonController.persistentContainer.save(context: context)
                 })
             ]
         } else {

Tusker/Views/Attachments/AttachmentsContainerView.swift

@@ -33,9 +33,17 @@ class AttachmentsContainerView: UIView {
         }
     }
     
-    override func awakeFromNib() {
-        super.awakeFromNib()
+    override init(frame: CGRect) {
+        super.init(frame: frame)
+        commonInit()
+    }
     
+    required init?(coder: NSCoder) {
+        super.init(coder: coder)
+        commonInit()
+    }
+    
+    private func commonInit() {
         self.isUserInteractionEnabled = true
         self.layer.cornerRadius = 5
         self.layer.masksToBounds = true

Tusker/Views/Poll/StatusPollView.swift

@@ -170,9 +170,7 @@ class StatusPollView: UIView {
                         return
                     }
                     status.poll = poll
-                    if container.viewContext.hasChanges {
-                        try! container.viewContext.save()
-                    }
+                    container.save(context: container.viewContext)
                     container.statusSubject.send(status.id)
                 }
             }

Tusker/Views/Status/StatusCollectionViewCell.swift

@@ -85,13 +85,12 @@ extension StatusCollectionViewCell {
         
         contentContainer.contentTextView.setTextFrom(status: status)
         contentContainer.attachmentsView.delegate = self
+        contentContainer.attachmentsView.updateUI(status: status)
         contentContainer.cardView.updateUI(status: status)
         contentContainer.cardView.isHidden = status.card == nil
         contentContainer.cardView.navigationDelegate = delegate
         contentContainer.cardView.actionProvider = delegate
         
-        contentContainer.attachmentsView.updateUI(status: status)
-        
         updateStatusState(status: status)
         
         contentWarningLabel.text = status.spoilerText