Improve scroll perform when loading new rows into table views

Instead of reloading the whole table view, only insert the rows for
statuses/notifications that were added.

Pachyderm/Client.swift

@@ -81,7 +81,7 @@ public class Client {
     }
     
     func createURLRequest<Result>(request: Request<Result>) -> URLRequest? {
-        guard var components = URLComponents(url: request.baseURL ?? baseURL, resolvingAgainstBaseURL: true) else { return nil }
+        guard var components = URLComponents(url: baseURL, resolvingAgainstBaseURL: true) else { return nil }
         components.path = request.path
         components.queryItems = request.queryParameters.queryItems
         guard let url = components.url else { return nil }

Pachyderm/Model/Timeline.swift

@@ -11,7 +11,6 @@ import Foundation
 public enum Timeline {
     case home
     case `public`(local: Bool)
-    case instance(instanceURL: URL)
     case tag(hashtag: String)
     case list(id: String)
     case direct
@@ -22,7 +21,7 @@ extension Timeline {
         switch self {
         case .home:
             return "/api/v1/timelines/home"
-        case .public, .instance(_):
+        case .public:
             return "/api/v1/timelines/public"
         case let .tag(hashtag):
             return "/api/v1/timelines/tag/\(hashtag)"
@@ -34,12 +33,7 @@ extension Timeline {
     }
     
     func request(range: RequestRange) -> Request<[Status]> {
-        var request: Request<[Status]>
-        if case let .instance(instanceURL) = self {
-            request = Request<[Status]>(method: .get, baseURL: instanceURL, path: endpoint)
-        } else {
-            request = Request<[Status]>(method: .get, path: endpoint)
-        }
+        var request: Request<[Status]> = Request<[Status]>(method: .get, path: endpoint)
         if case .public(true) = self {
             request.queryParameters.append("local" => true)
         }
@@ -57,8 +51,6 @@ extension Timeline: Codable {
             self = .home
         case "public":
             self = .public(local: try container.decode(Bool.self, forKey: .local))
-        case "instanceURL":
-            self = .instance(instanceURL: try container.decode(URL.self, forKey: .instanceURL))
         case "tag":
             self = .tag(hashtag: try container.decode(String.self, forKey: .hashtag))
         case "list":
@@ -78,9 +70,6 @@ extension Timeline: Codable {
         case let .public(local):
             try container.encode("public", forKey: .type)
             try container.encode(local, forKey: .local)
-        case let .instance(instanceURL):
-            try container.encode("instanceURL", forKey: .type)
-            try container.encode(instanceURL, forKey: .instanceURL)
         case let .tag(hashtag):
             try container.encode("tag", forKey: .type)
             try container.encode(hashtag, forKey: .hashtag)
@@ -95,7 +84,6 @@ extension Timeline: Codable {
     enum CodingKeys: String, CodingKey {
         case type
         case local
-        case instanceURL
         case hashtag
         case listID
     }

Pachyderm/Request/Request.swift

@@ -10,14 +10,12 @@ import Foundation
 
 public struct Request<ResultType: Decodable> {
     let method: Method
-    let baseURL: URL?
     let path: String
     let body: Body
     var queryParameters: [Parameter]
     
-    init(method: Method, baseURL: URL? = nil, path: String, body: Body = .empty, queryParameters: [Parameter] = []) {
+    init(method: Method, path: String, body: Body = .empty, queryParameters: [Parameter] = []) {
         self.method = method
-        self.baseURL = baseURL
         self.path = path
         self.body = body
         self.queryParameters = queryParameters

Tusker/Caching/ImageCache.swift

@@ -12,13 +12,13 @@ import Cache
 class ImageCache {
     
     static let avatars = ImageCache(name: "Avatars", memoryExpiry: .seconds(60 * 60), diskExpiry: .seconds(60 * 60 * 24))
-    static let headers = ImageCache(name: "Headers", memoryExpiry: .seconds(60 * 60), diskExpiry: .seconds(60 * 60 * 24))
+    static let headers = ImageCache(name: "Headers", memoryExpiry: .seconds(60 * 5), diskExpiry: .seconds(60 * 60))
     static let attachments = ImageCache(name: "Attachments", memoryExpiry: .seconds(60 * 2))
     static let emojis = ImageCache(name: "Emojis", memoryExpiry: .seconds(60 * 5), diskExpiry: .seconds(60 * 60))
 
     let cache: Cache<Data>
     
-    var requests = [URL: Request]()
+    var requests = [URL: RequestGroup]()
     
     init(name: String, memoryExpiry expiry: Expiry) {
         let storage = MemoryStorage<Data>(config: MemoryConfig(expiry: expiry))
@@ -36,20 +36,22 @@ class ImageCache {
         self.cache = .hybrid(HybridStorage(memoryStorage: memory, diskStorage: disk))
     }
     
-    func get(_ url: URL, completion: ((Data?) -> Void)?) {
+    func get(_ url: URL, completion: ((Data?) -> Void)?) -> Request? {
         let key = url.absoluteString
         if (try? cache.existsObject(forKey: key)) ?? false,
             let data = try? cache.object(forKey: key) {
             completion?(data)
+            return nil
         } else {
-            if let completion = completion, let request = requests[url] {
-                request.callbacks.append(completion)
+            if let completion = completion, let group = requests[url] {
+                return group.addCallback(completion)
             } else {
-                let request = Request(url: url, completion: completion)
-                requests[url] = request
-                request.run { (data) in
+                let group = RequestGroup(url: url)
+                let request = group.addCallback(completion)
+                group.run { (data) in
                     try? self.cache.setObject(data, forKey: key)
                 }
+                return request
             }
         }
     }
@@ -58,24 +60,23 @@ class ImageCache {
         return try? cache.object(forKey: url.absoluteString)
     }
 
-    func cancel(_ url: URL) {
-        requests[url]?.cancel()
+    func cancelWithoutCallback(_ url: URL) {
+        requests[url]?.cancelWithoutCallback()
     }
     
-    class Request {
+    class RequestGroup {
         let url: URL
-        var task: URLSessionDataTask?
-        var callbacks: [(Data?) -> Void]
+        private var task: URLSessionDataTask?
+        private var requests = [Request]()
 
-        init(url: URL, completion: ((Data?) -> Void)?) {
-            if let completion = completion {
-                self.callbacks = [completion]
-            } else {
-                self.callbacks = []
-            }
+        init(url: URL) {
             self.url = url
         }
 
+        deinit {
+            task?.cancel()
+        }
+        
         func run(cache: @escaping (Data) -> Void) {
             task = URLSession.shared.dataTask(with: url, completionHandler: { (data, response, error) in
                 guard error == nil, let data = data else {
@@ -88,13 +89,56 @@ class ImageCache {
             task!.resume()
         }
         
-        func cancel() {
-            task?.cancel()
-            complete(with: nil)
+        private func updatePriority() {
+            task?.priority = max(1.0, URLSessionTask.defaultPriority + 0.1 * Float(requests.filter { !$0.cancelled }.count))
+        }
+        
+        func addCallback(_ completion: ((Data?) -> Void)?) -> Request {
+            let request = Request(callback: completion)
+            requests.append(request)
+            updatePriority()
+            return request
+        }
+        
+        func cancelWithoutCallback() {
+            if let request = requests.first(where: { $0.callback == nil && !$0.cancelled }) {
+                request.cancel()
+                updatePriority()
+            }
+        }
+        
+        fileprivate func requestCancelled() {
+            let remaining = requests.filter { !$0.cancelled }.count
+            if remaining <= 0 {
+                task?.cancel()
+                complete(with: nil)
+            } else {
+                updatePriority()
+            }
         }
 
         func complete(with data: Data?) {
-            callbacks.forEach { $0(data) }
+            requests.filter { !$0.cancelled }.forEach {
+                if let callback = $0.callback {
+                    callback(data)
+                }
+            }
+        }
+    }
+    
+    class Request {
+        weak var group: RequestGroup?
+        private(set) var callback: ((Data?) -> Void)?
+        private(set) var cancelled: Bool = false
+        
+        init(callback: ((Data?) -> Void)?) {
+            self.callback = callback
+        }
+        
+        func cancel() {
+            cancelled = true
+            callback = nil
+            group?.requestCancelled()
         }
     }
     

Tusker/Extensions/Timline+UI.swift

@@ -16,8 +16,6 @@ extension Timeline {
             return "Home"
         case let .public(local):
             return local ? "Local" : "Federated"
-        case let .instance(instance):
-            return instance.host!
         case let .tag(hashtag):
             return "#\(hashtag)"
         case .list:
@@ -37,8 +35,6 @@ extension Timeline {
             } else {
                 return UIImage(systemName: "globe")
             }
-        case .instance(_):
-            return UIImage(systemName: "globe")
         default:
             return nil
         }

Tusker/Screens/Attachment/AttachmentViewController.swift

@@ -15,6 +15,8 @@ class AttachmentViewController: UIViewController {
     var largeImageVC: LargeImageViewController?
     var loadingVC: LoadingViewController?
     
+    var attachmentRequest: ImageCache.Request?
+    
     private var initialControlsVisible: Bool = true
     var controlsVisible: Bool {
         get {
@@ -51,15 +53,25 @@ class AttachmentViewController: UIViewController {
         } else {
             loadingVC = LoadingViewController()
             embedChild(loadingVC!)
-            ImageCache.attachments.get(attachment.url) { [weak self] (data) in
+            attachmentRequest = ImageCache.attachments.get(attachment.url) { [weak self] (data) in
+                guard let self = self else { return }
+                self.attachmentRequest = nil
                 DispatchQueue.main.async {
-                    self?.loadingVC?.removeViewAndController()
-                    self?.createLargeImage(data: data!)
+                    self.loadingVC?.removeViewAndController()
+                    self.createLargeImage(data: data!)
                 }
             }
         }
     }
     
+    override func didMove(toParent parent: UIViewController?) {
+        super.didMove(toParent: parent)
+        
+        if parent == nil {
+            attachmentRequest?.cancel()
+        }
+    }
+    
     func createLargeImage(data: Data) {
         guard let image = UIImage(data: data) else { return }
         largeImageVC = LargeImageViewController(image: image, description: attachment.description, sourceInfo: nil)

Tusker/Screens/Bookmarks/BookmarksTableViewController.swift

@@ -15,13 +15,7 @@ class BookmarksTableViewController: EnhancedTableViewController {
 
     let mastodonController: MastodonController
     
-    var statuses: [(id: String, state: StatusState)] = [] {
-        didSet {
-            DispatchQueue.main.async {
-                self.tableView.reloadData()
-            }
-        }
-    }
+    var statuses: [(id: String, state: StatusState)] = []
     
     var newer: RequestRange?
     var older: RequestRange?
@@ -55,6 +49,10 @@ class BookmarksTableViewController: EnhancedTableViewController {
             self.statuses.append(contentsOf: statuses.map { ($0.id, .unknown) })
             self.newer = pagination?.newer
             self.older = pagination?.older
+            
+            DispatchQueue.main.async {
+                self.tableView.reloadData()
+            }
         }
         
         userActivity = UserActivityManager.bookmarksActivity()
@@ -90,7 +88,14 @@ class BookmarksTableViewController: EnhancedTableViewController {
             guard case let .success(newStatuses, pagination) = response else { fatalError() }
             self.older = pagination?.older
             self.mastodonController.cache.addAll(statuses: newStatuses)
+            let newIndexPaths = (self.statuses.count..<(self.statuses.count + newStatuses.count)).map {
+                IndexPath(row: $0, section: 0)
+            }
             self.statuses.append(contentsOf: newStatuses.map { ($0.id, .unknown) })
+            
+            DispatchQueue.main.async {
+                self.tableView.insertRows(at: newIndexPaths, with: .automatic)
+            }
         }
     }
     
@@ -159,9 +164,9 @@ extension BookmarksTableViewController: UITableViewDataSourcePrefetching {
     func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
         for indexPath in indexPaths {
             guard let status = mastodonController.cache.status(for: statuses[indexPath.row].id) else { continue }
-            ImageCache.avatars.get(status.account.avatar, completion: nil)
+            _ = ImageCache.avatars.get(status.account.avatar, completion: nil)
             for attachment in status.attachments where attachment.kind == .image {
-                ImageCache.attachments.get(attachment.url, completion: nil)
+                _ = ImageCache.attachments.get(attachment.url, completion: nil)
             }
         }
     }
@@ -169,9 +174,9 @@ extension BookmarksTableViewController: UITableViewDataSourcePrefetching {
     func tableView(_ tableView: UITableView, cancelPrefetchingForRowsAt indexPaths: [IndexPath]) {
         for indexPath in indexPaths {
             guard let status = mastodonController.cache.status(for: statuses[indexPath.row].id) else { continue }
-            ImageCache.avatars.cancel(status.account.avatar)
+            ImageCache.avatars.cancelWithoutCallback(status.account.avatar)
             for attachment in status.attachments where attachment.kind == .image {
-                ImageCache.attachments.cancel(attachment.url)
+                ImageCache.attachments.cancelWithoutCallback(attachment.url)
             }
         }
     }

Tusker/Screens/Conversation/ConversationTableViewController.swift

@@ -170,9 +170,9 @@ extension ConversationTableViewController: UITableViewDataSourcePrefetching {
     func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
         for indexPath in indexPaths {
             guard let status = mastodonController.cache.status(for: statuses[indexPath.row].id) else { continue }
-            ImageCache.avatars.get(status.account.avatar, completion: nil)
+            _ = ImageCache.avatars.get(status.account.avatar, completion: nil)
             for attachment in status.attachments {
-                ImageCache.attachments.get(attachment.url, completion: nil)
+                _ = ImageCache.attachments.get(attachment.url, completion: nil)
             }
         }
     }
@@ -180,9 +180,9 @@ extension ConversationTableViewController: UITableViewDataSourcePrefetching {
     func tableView(_ tableView: UITableView, cancelPrefetchingForRowsAt indexPaths: [IndexPath]) {
         for indexPath in indexPaths {
             guard let status = mastodonController.cache.status(for: statuses[indexPath.row].id) else { continue }
-            ImageCache.avatars.cancel(status.account.avatar)
+            ImageCache.avatars.cancelWithoutCallback(status.account.avatar)
             for attachment in status.attachments {
-                ImageCache.attachments.cancel(attachment.url)
+                ImageCache.attachments.cancelWithoutCallback(attachment.url)
             }
         }
     }

Tusker/Screens/Notifications/NotificationsTableViewController.swift

@@ -21,13 +21,7 @@ class NotificationsTableViewController: EnhancedTableViewController {
     let excludedTypes: [Pachyderm.Notification.Kind]
     let groupTypes = [Notification.Kind.favourite, .reblog, .follow]
 
-    var groups: [NotificationGroup] = [] {
-        didSet {
-            DispatchQueue.main.async {
-                self.tableView.reloadData()
-            }
-        }
-    }
+    var groups: [NotificationGroup] = []
     
     var newer: RequestRange?
     var older: RequestRange?
@@ -73,6 +67,10 @@ class NotificationsTableViewController: EnhancedTableViewController {
             
             self.newer = pagination?.newer
             self.older = pagination?.older
+            
+            DispatchQueue.main.async {
+                self.tableView.reloadData()
+            }
         }
     }
     
@@ -133,6 +131,9 @@ class NotificationsTableViewController: EnhancedTableViewController {
                 
                 let groups = NotificationGroup.createGroups(notifications: newNotifications, only: self.groupTypes)
                 
+                let newIndexPaths = (self.groups.count..<(self.groups.count + groups.count)).map {
+                    IndexPath(row: $0, section: 0)
+                }
                 self.groups.append(contentsOf: groups)
                 
                 self.mastodonController.cache.addAll(notifications: newNotifications)
@@ -140,6 +141,10 @@ class NotificationsTableViewController: EnhancedTableViewController {
                 self.mastodonController.cache.addAll(accounts: newNotifications.map { $0.account })
 
                 self.older = pagination?.older
+                
+                DispatchQueue.main.async {
+                    self.tableView.insertRows(at: newIndexPaths, with: .automatic)
+                }
             }
         }
     }
@@ -216,6 +221,11 @@ class NotificationsTableViewController: EnhancedTableViewController {
             }
 
             DispatchQueue.main.async {
+                let newIndexPaths = (0..<groups.count).map {
+                    IndexPath(row: $0, section: 0)
+                }
+                self.tableView.insertRows(at: newIndexPaths, with: .automatic)
+                
                 self.refreshControl?.endRefreshing()
                 
                 // maintain the current position in the list (don't scroll to top)
@@ -240,7 +250,7 @@ extension NotificationsTableViewController: UITableViewDataSourcePrefetching {
         for indexPath in indexPaths {
             for notificationID in groups[indexPath.row].notificationIDs {
                 guard let notification = mastodonController.cache.notification(for: notificationID) else { continue }
-                ImageCache.avatars.get(notification.account.avatar, completion: nil)
+                _ = ImageCache.avatars.get(notification.account.avatar, completion: nil)
             }
         }
     }
@@ -249,7 +259,7 @@ extension NotificationsTableViewController: UITableViewDataSourcePrefetching {
         for indexPath in indexPaths {
             for notificationID in groups[indexPath.row].notificationIDs {
                 guard let notification = mastodonController.cache.notification(for: notificationID) else { continue }
-                ImageCache.avatars.cancel(notification.account.avatar)
+                ImageCache.avatars.cancelWithoutCallback(notification.account.avatar)
             }
         }
     }

Tusker/Screens/Profile/MyProfileTableViewController.swift

@@ -21,8 +21,8 @@ class MyProfileTableViewController: ProfileTableViewController {
         mastodonController.getOwnAccount { (account) in
             self.accountID = account.id
             
-            ImageCache.avatars.get(account.avatar, completion: { (data) in
-                guard let data = data, let image = UIImage(data: data) else { return }
+            _ = ImageCache.avatars.get(account.avatar, completion: { [weak self] (data) in
+                guard let self = self, let data = data, let image = UIImage(data: data) else { return }
                 DispatchQueue.main.async {
                     let size = CGSize(width: 30, height: 30)
                     let tabBarImage = UIGraphicsImageRenderer(size: size).image { (_) in

Tusker/Screens/Profile/ProfileTableViewController.swift

@@ -294,9 +294,9 @@ extension ProfileTableViewController: UITableViewDataSourcePrefetching {
         for indexPath in indexPaths where indexPath.section > 1 {
             let statusID = timelineSegments[indexPath.section - 2][indexPath.row].id
             guard let status = mastodonController.cache.status(for: statusID) else { continue }
-            ImageCache.avatars.get(status.account.avatar, completion: nil)
+            _ = ImageCache.avatars.get(status.account.avatar, completion: nil)
             for attachment in status.attachments {
-                ImageCache.attachments.get(attachment.url, completion: nil)
+                _ = ImageCache.attachments.get(attachment.url, completion: nil)
             }
         }
     }
@@ -305,9 +305,9 @@ extension ProfileTableViewController: UITableViewDataSourcePrefetching {
         for indexPath in indexPaths where indexPath.section > 1 {
             let statusID = timelineSegments[indexPath.section - 2][indexPath.row].id
             guard let status = mastodonController.cache.status(for: statusID) else { continue }
-            ImageCache.avatars.cancel(status.account.avatar)
+            ImageCache.avatars.cancelWithoutCallback(status.account.avatar)
             for attachment in status.attachments {
-                ImageCache.attachments.cancel(attachment.url)
+                ImageCache.attachments.cancelWithoutCallback(attachment.url)
             }
         }
     }

Tusker/Screens/Timeline/InstanceTimelineViewController.swift

@@ -39,7 +39,10 @@ class InstanceTimelineViewController: TimelineTableViewController {
         // the timeline VC only stores a weak reference to it, so we need to store a strong reference to make sure it's not released immediately
         instanceMastodonController = MastodonController(instanceURL: url)
 
-        super.init(for: .instance(instanceURL: url), mastodonController: instanceMastodonController)
+        super.init(for: .public(local: true), mastodonController: instanceMastodonController)
+        
+        title = url.host!
+        userActivity = nil // todo: activity for instance-specific timelines
     }
     
     required init?(coder aDecoder: NSCoder) {
@@ -74,6 +77,27 @@ class InstanceTimelineViewController: TimelineTableViewController {
         // no-op, we don't currently support viewing whole conversations from other instances
     }
     
+    override func tableView(_ tableView: UITableView, contextMenuConfigurationForRowAt indexPath: IndexPath, point: CGPoint) -> UIContextMenuConfiguration? {
+        // don't show other screens or actions for other instances
+        return nil
+    }
+    
+    override func tableView(_ tableView: UITableView, leadingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
+        // don't show swipe actions for other instances
+        return nil
+    }
+    
+    override func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
+        // only show more actions for other instances
+        let more = UIContextualAction(style: .normal, title: "More") { (action, view, completion) in
+            completion(true)
+            self.showMoreOptions(forStatus: self.timelineSegments[indexPath.section][indexPath.row].id, sourceView: tableView.cellForRow(at: indexPath))
+        }
+        more.image = UIImage(systemName: "ellipsis.circle.fill")
+        more.backgroundColor = .lightGray
+        return UISwipeActionsConfiguration(actions: [more])
+    }
+    
     // MARK: - Interaction
     @objc func toggleSaveButtonPressed() {
         if SavedDataManager.shared.isSaved(instance: instanceURL, for: parentMastodonController!.accountInfo!) {

Tusker/Screens/Timeline/TimelineTableViewController.swift

@@ -14,13 +14,7 @@ class TimelineTableViewController: EnhancedTableViewController {
     var timeline: Timeline!
     weak var mastodonController: MastodonController!
     
-    var timelineSegments: [[(id: String, state: StatusState)]] = [] {
-        didSet {
-            DispatchQueue.main.async {
-                self.tableView.reloadData()
-            }
-        }
-    }
+    var timelineSegments: [[(id: String, state: StatusState)]] = []
     
     var newer: RequestRange?
     var older: RequestRange?
@@ -69,6 +63,9 @@ class TimelineTableViewController: EnhancedTableViewController {
             self.timelineSegments.insert(statuses.map { ($0.id, .unknown) }, at: 0)
             self.newer = pagination?.newer
             self.older = pagination?.older
+            DispatchQueue.main.async {
+                self.tableView.reloadData()
+            }
         }
     }
 
@@ -105,7 +102,12 @@ class TimelineTableViewController: EnhancedTableViewController {
                 guard case let .success(newStatuses, pagination) = response else { fatalError() }
                 self.older = pagination?.older
                 self.mastodonController.cache.addAll(statuses: newStatuses)
+                let newRows = self.timelineSegments.last!.count..<(self.timelineSegments.last!.count + newStatuses.count)
+                let newIndexPaths = newRows.map { IndexPath(row: $0, section: self.timelineSegments.count - 1) }
                 self.timelineSegments[self.timelineSegments.count - 1].append(contentsOf: newStatuses.map { ($0.id, .unknown) })
+                DispatchQueue.main.async {
+                    self.tableView.insertRows(at: newIndexPaths, with: .none)
+                }
             }
         }
     }
@@ -137,6 +139,11 @@ class TimelineTableViewController: EnhancedTableViewController {
             }
             
             DispatchQueue.main.async {
+                let newIndexPaths = (0..<newStatuses.count).map {
+                    IndexPath(row: $0, section: 0)
+                }
+                self.tableView.insertRows(at: newIndexPaths, with: .automatic)
+
                 self.refreshControl?.endRefreshing()
                 
                 // maintain the current position in the list (don't scroll to the top)
@@ -165,9 +172,9 @@ extension TimelineTableViewController: UITableViewDataSourcePrefetching {
     func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
         for indexPath in indexPaths {
             guard let status = mastodonController.cache.status(for: statusID(for: indexPath)) else { continue }
-            ImageCache.avatars.get(status.account.avatar, completion: nil)
+            _ = ImageCache.avatars.get(status.account.avatar, completion: nil)
             for attachment in status.attachments {
-                ImageCache.attachments.get(attachment.url, completion: nil)
+                _ = ImageCache.attachments.get(attachment.url, completion: nil)
             }
         }
     }
@@ -175,9 +182,9 @@ extension TimelineTableViewController: UITableViewDataSourcePrefetching {
     func tableView(_ tableView: UITableView, cancelPrefetchingForRowsAt indexPaths: [IndexPath]) {
         for indexPath in indexPaths {
             guard let status = mastodonController.cache.status(for: statusID(for: indexPath)) else { continue }
-            ImageCache.avatars.cancel(status.account.avatar)
+            ImageCache.avatars.cancelWithoutCallback(status.account.avatar)
             for attachment in status.attachments {
-                ImageCache.attachments.cancel(attachment.url)
+                ImageCache.attachments.cancelWithoutCallback(attachment.url)
             }
         }
     }

Tusker/Shortcuts/UserActivityManager.swift

@@ -111,9 +111,6 @@ class UserActivityManager {
         case .public(local: false):
             activity.title = NSLocalizedString("Show Federated Timeline", comment: "federated timeline shortcut title")
             activity.suggestedInvocationPhrase = NSLocalizedString("Show my federated timeline", comment: "federated timeline invocation phrase")
-        case let .instance(instance):
-            activity.title = String(format: NSLocalizedString("Show %@", comment: "show instance timeline shortcut title"), instance.host!)
-            activity.suggestedInvocationPhrase = String(format: NSLocalizedString("Show the instance %@", comment: "instance timeline shortcut invocation phrase"), instance.host!)
         case let .tag(hashtag):
             activity.title = String(format: NSLocalizedString("Show #%@", comment: "show hashtag shortcut title"), hashtag)
             activity.suggestedInvocationPhrase = String(format: NSLocalizedString("Show the %@ hashtag", comment: "hashtag shortcut invocation phrase"), hashtag)

Tusker/Views/Account Cell/AccountTableViewCell.swift

@@ -19,7 +19,7 @@ class AccountTableViewCell: UITableViewCell {
     
     var accountID: String!
     
-    var avatarURL: URL?
+    var avatarRequest: ImageCache.Request?
     
     override func awakeFromNib() {
         super.awakeFromNib()
@@ -44,9 +44,9 @@ class AccountTableViewCell: UITableViewCell {
             fatalError("Missing cached account \(accountID)")
         }
         
-        self.avatarURL = account.avatar
-        ImageCache.avatars.get(account.avatar) { (data) in
-            guard let data = data, self.avatarURL == account.avatar else { return }
+        avatarRequest = ImageCache.avatars.get(account.avatar) { [weak self] (data) in
+            guard let self = self, let data = data, self.accountID == accountID else { return }
+            self.avatarRequest = nil
             DispatchQueue.main.async {
                 self.avatarImageView.image = UIImage(data: data)
             }
@@ -57,6 +57,12 @@ class AccountTableViewCell: UITableViewCell {
         updateUIForPrefrences()
     }
     
+    override func prepareForReuse() {
+        super.prepareForReuse()
+        
+        avatarRequest?.cancel()
+    }
+
 }
 
 extension AccountTableViewCell: SelectableTableViewCell {

Tusker/Views/Account Detail/LargeAccountDetailView.swift

@@ -15,6 +15,8 @@ class LargeAccountDetailView: UIView {
     var displayNameLabel = UILabel()
     var usernameLabel = UILabel()
     
+    var avatarRequest: ImageCache.Request?
+    
     required init?(coder aDecoder: NSCoder) {
         super.init(coder: aDecoder)
         
@@ -49,6 +51,10 @@ class LargeAccountDetailView: UIView {
         NotificationCenter.default.addObserver(self, selector: #selector(updateUIForPreferences), name: .preferencesChanged, object: nil)
     }
     
+    deinit {
+        avatarRequest?.cancel()
+    }
+    
     override func layoutSubviews() {
         super.layoutSubviews()
         
@@ -63,8 +69,9 @@ class LargeAccountDetailView: UIView {
         displayNameLabel.text = account.realDisplayName
         usernameLabel.text = "@\(account.acct)"
         
-        ImageCache.avatars.get(account.avatar) { (data) in
-            guard let data = data else { return }
+        avatarRequest = ImageCache.avatars.get(account.avatar) { [weak self] (data) in
+            guard let self = self, let data = data else { return }
+            self.avatarRequest = nil
             DispatchQueue.main.async {
                 self.avatarImageView.image = UIImage(data: data)
             }

Tusker/Views/Attachments/AttachmentView.swift

@@ -24,6 +24,8 @@ class AttachmentView: UIImageView, GIFAnimatable {
     var attachment: Attachment!
     var index: Int!
     
+    private var attachmentRequest: ImageCache.Request?
+    
     var gifData: Data?
 
     public lazy var animator: Animator? = Animator(withDelegate: self)
@@ -37,6 +39,10 @@ class AttachmentView: UIImageView, GIFAnimatable {
         loadAttachment()
     }
     
+    deinit {
+        attachmentRequest?.cancel()
+    }
+    
     required init?(coder aDecoder: NSCoder) {
         super.init(coder: aDecoder)
         commonInit()
@@ -71,8 +77,9 @@ class AttachmentView: UIImageView, GIFAnimatable {
     }
     
     func loadImage() {
-        ImageCache.attachments.get(attachment.url) { [weak self] (data) in
+        attachmentRequest = ImageCache.attachments.get(attachment.url) { [weak self] (data) in
             guard let self = self, let data = data else { return }
+            self.attachmentRequest = nil
             DispatchQueue.main.async {
                 if self.attachment.url.pathExtension == "gif" {
                     self.animate(withGIFData: data)
@@ -87,12 +94,14 @@ class AttachmentView: UIImageView, GIFAnimatable {
     }
     
     func loadVideo() {
+        let attachmentURL = self.attachment.url
         DispatchQueue.global(qos: .userInitiated).async {
-            let asset = AVURLAsset(url: self.attachment.url)
+            let asset = AVURLAsset(url: attachmentURL)
             let generator = AVAssetImageGenerator(asset: asset)
             generator.appliesPreferredTrackTransform = true
             guard let image = try? generator.copyCGImage(at: CMTime(seconds: 0, preferredTimescale: 1), actualTime: nil) else { return }
             DispatchQueue.main.async {
+                guard self.attachment.url == attachmentURL else { return }
                 self.image = UIImage(cgImage: image)
             }
         }

Tusker/Views/Compose Status Reply/ComposeStatusReplyView.swift

@@ -18,10 +18,16 @@ class ComposeStatusReplyView: UIView {
     @IBOutlet weak var usernameLabel: UILabel!
     @IBOutlet weak var statusContentTextView: StatusContentTextView!
     
+    var avatarRequest: ImageCache.Request?
+    
     static func create() -> ComposeStatusReplyView {
         return UINib(nibName: "ComposeStatusReplyView", bundle: nil).instantiate(withOwner: nil, options: nil).first as! ComposeStatusReplyView
     }
     
+    deinit {
+        avatarRequest?.cancel()
+    }
+
     override func awakeFromNib() {
         super.awakeFromNib()
         
@@ -39,8 +45,8 @@ class ComposeStatusReplyView: UIView {
         statusContentTextView.overrideMastodonController = mastodonController
         statusContentTextView.statusID = status.id
         
-        ImageCache.avatars.get(status.account.avatar) { (data) in
-            guard let data = data else { return }
+        avatarRequest = ImageCache.avatars.get(status.account.avatar) { [weak self] (data) in
+            guard let self = self, let data = data else { return }
             DispatchQueue.main.async {
                 self.avatarImageView.image = UIImage(data: data)
             }

Tusker/Views/ContentTextView.swift

@@ -49,7 +49,7 @@ class ContentTextView: LinkTextView {
         
         for emoji in emojis {
             group.enter()
-            ImageCache.emojis.get(emoji.url) { (data) in
+            _ = ImageCache.emojis.get(emoji.url) { (data) in
                 defer { group.leave() }
                 guard let data = data, let image = UIImage(data: data) else {
                     return

Tusker/Views/Instance Cell/InstanceTableViewCell.swift

@@ -20,6 +20,7 @@ class InstanceTableViewCell: UITableViewCell {
     var selectorInstance: InstanceSelector.Instance?
     
     var thumbnailURL: URL?
+    var thumbnailRequest: ImageCache.Request?
     
     override func awakeFromNib() {
         super.awakeFromNib()
@@ -59,12 +60,21 @@ class InstanceTableViewCell: UITableViewCell {
     private func updateThumbnail(url: URL) {
         thumbnailImageView.image = nil
         thumbnailURL = url
-        ImageCache.attachments.get(url) { (data) in
-            guard self.thumbnailURL == url, let data = data, let image = UIImage(data: data) else { return }
+        thumbnailRequest = ImageCache.attachments.get(url) { [weak self] (data) in
+            guard let self = self, self.thumbnailURL == url, let data = data, let image = UIImage(data: data) else { return }
+            self.thumbnailRequest = nil
             DispatchQueue.main.async {
                 self.thumbnailImageView.image = image
             }
         }
     }
     
+    override func prepareForReuse() {
+        super.prepareForReuse()
+        
+        thumbnailRequest?.cancel()
+        instance = nil
+        selectorInstance = nil
+    }
+
 }

Tusker/Views/Notifications/ActionNotificationGroupTableViewCell.swift

@@ -24,7 +24,7 @@ class ActionNotificationGroupTableViewCell: UITableViewCell {
     var group: NotificationGroup!
     var statusID: String!
     
-    var authorAvatarURL: URL?
+    var avatarRequests = [String: ImageCache.Request]()
     var updateTimestampWorkItem: DispatchWorkItem?
     
     deinit {
@@ -75,9 +75,10 @@ class ActionNotificationGroupTableViewCell: UITableViewCell {
             imageView.translatesAutoresizingMaskIntoConstraints = false
             imageView.layer.masksToBounds = true
             imageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadiusFraction * 30
-            ImageCache.avatars.get(account.avatar) { (data) in
-                guard let data = data, self.group.id == group.id else { return }
+            avatarRequests[account.id] = ImageCache.avatars.get(account.avatar) { [weak self] (data) in
+                guard let self = self, let data = data, self.group.id == group.id else { return }
                 DispatchQueue.main.async {
+                    self.avatarRequests.removeValue(forKey: account.id)
                     imageView.image = UIImage(data: data)
                 }
             }
@@ -149,10 +150,7 @@ class ActionNotificationGroupTableViewCell: UITableViewCell {
     override func prepareForReuse() {
         super.prepareForReuse()
         
-        if let authorAvatarURL = authorAvatarURL {
-            ImageCache.avatars.cancel(authorAvatarURL)
-        }
-        
+        avatarRequests.values.forEach { $0.cancel() }
         updateTimestampWorkItem?.cancel()
         updateTimestampWorkItem = nil
     }

Tusker/Views/Notifications/FollowNotificationGroupTableViewCell.swift

@@ -20,6 +20,7 @@ class FollowNotificationGroupTableViewCell: UITableViewCell {
     
     var group: NotificationGroup!
     
+    var avatarRequests = [String: ImageCache.Request]()
     var updateTimestampWorkItem: DispatchWorkItem?
     
     deinit {
@@ -55,9 +56,10 @@ class FollowNotificationGroupTableViewCell: UITableViewCell {
             imageView.translatesAutoresizingMaskIntoConstraints = false
             imageView.layer.masksToBounds = true
             imageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadiusFraction * 30
-            ImageCache.avatars.get(account.avatar) { (data) in
-                guard let data = data, self.group.id == group.id else { return }
+            avatarRequests[account.id] = ImageCache.avatars.get(account.avatar) { [weak self] (data) in
+                guard let self = self, let data = data, self.group.id == group.id else { return }
                 DispatchQueue.main.async {
+                    self.avatarRequests.removeValue(forKey: account.id)
                     imageView.image = UIImage(data: data)
                 }
             }
@@ -114,6 +116,7 @@ class FollowNotificationGroupTableViewCell: UITableViewCell {
     override func prepareForReuse() {
         super.prepareForReuse()
         
+        avatarRequests.values.forEach { $0.cancel() }
         updateTimestampWorkItem?.cancel()
         updateTimestampWorkItem = nil
     }
@@ -139,15 +142,19 @@ extension FollowNotificationGroupTableViewCell: MenuPreviewProvider {
     
     func getPreviewProviders(for location: CGPoint, sourceViewController: UIViewController) -> PreviewProviders? {
         guard let mastodonController = mastodonController else { return nil }
+        let accountIDs = self.group.notificationIDs.compactMap(mastodonController.cache.notification(for:)).map { $0.account.id }
         return (content: {
-            let accountIDs = self.group.notificationIDs.compactMap(mastodonController.cache.notification(for:)).map { $0.account.id }
             if accountIDs.count == 1 {
                 return ProfileTableViewController(accountID: accountIDs.first!, mastodonController: mastodonController)
             } else {
                 return AccountListTableViewController(accountIDs: accountIDs, mastodonController: mastodonController)
             }
         }, actions: {
-            return []
+            if accountIDs.count == 1 {
+                return self.actionsForProfile(accountID: accountIDs.first!, sourceView: self)
+            } else {
+                return []
+            }
         })
     }
 }

Tusker/Views/Notifications/FollowRequestNotificationTableViewCell.swift

@@ -25,6 +25,7 @@ class FollowRequestNotificationTableViewCell: UITableViewCell {
     var notification: Pachyderm.Notification?
     var account: Account!
     
+    var avatarRequest: ImageCache.Request?
     var updateTimestampWorkItem: DispatchWorkItem?
     
     deinit {
@@ -53,8 +54,9 @@ class FollowRequestNotificationTableViewCell: UITableViewCell {
     func updateUI(account: Account) {
         self.account = account
         actionLabel.text = "Request to follow from \(account.realDisplayName)"
-        ImageCache.avatars.get(account.avatar) { (data) in
-            guard self.account == account, let data = data, let image = UIImage(data: data) else { return }
+        avatarRequest = ImageCache.avatars.get(account.avatar) { [weak self] (data) in
+            guard let self = self, self.account == account, let data = data, let image = UIImage(data: data) else { return }
+            self.avatarRequest = nil
             DispatchQueue.main.async {
                 self.avatarImageView.image = image
             }
@@ -88,6 +90,7 @@ class FollowRequestNotificationTableViewCell: UITableViewCell {
     override func prepareForReuse() {
         super.prepareForReuse()
         
+        avatarRequest?.cancel()
         updateTimestampWorkItem?.cancel()
         updateTimestampWorkItem = nil
     }

Tusker/Views/Profile Header/ProfileHeaderTableViewCell.swift

@@ -32,8 +32,8 @@ class ProfileHeaderTableViewCell: UITableViewCell {
     
     var accountID: String!
     
-    var avatarURL: URL?
-    var headerURL: URL?
+    var avatarRequest: ImageCache.Request?
+    var headerRequest: ImageCache.Request?
     
     override func awakeFromNib() {
         avatarContainerView.layer.masksToBounds = true
@@ -63,19 +63,19 @@ class ProfileHeaderTableViewCell: UITableViewCell {
         usernameLabel.text = "@\(account.acct)"
         
         avatarImageView.image = nil
-        avatarURL = account.avatar
-        ImageCache.avatars.get(account.avatar) { (data) in
-            guard let data = data else { return }
+        avatarRequest = ImageCache.avatars.get(account.avatar) { [weak self] (data) in
+            guard let self = self, let data = data, self.accountID == accountID else { return }
+            self.avatarRequest = nil
             DispatchQueue.main.async {
                 self.avatarImageView.image = UIImage(data: data)
-                self.avatarURL = nil
             }
         }
-        ImageCache.headers.get(account.header) { (data) in
-            guard let data = data else { return }
+        headerImageView.image = nil
+        headerRequest = ImageCache.headers.get(account.header) { [weak self] (data) in
+            guard let self = self, let data = data, self.accountID == accountID else { return }
+            self.headerRequest = nil
             DispatchQueue.main.async {
                 self.headerImageView.image = UIImage(data: data)
-                self.headerURL = nil
             }
         }
         
@@ -131,12 +131,8 @@ class ProfileHeaderTableViewCell: UITableViewCell {
     }
     
     override func prepareForReuse() {
-        if let url = avatarURL {
-            ImageCache.avatars.cancel(url)
-        }
-        if let url = headerURL {
-            ImageCache.headers.cancel(url)
-        }
+        avatarRequest?.cancel()
+        headerRequest?.cancel()
     }
     
     @objc func morePressed() {

Tusker/Views/Status/BaseStatusTableViewCell.swift

@@ -64,8 +64,7 @@ class BaseStatusTableViewCell: UITableViewCell {
     }
     var showStatusAutomatically = false
     
-    var avatarURL: URL?
-    var attachmentDataTasks: [URLSessionDataTask] = []
+    private var avatarRequest: ImageCache.Request?
 
     private var statusUpdater: Cancellable?
     private var accountUpdater: Cancellable?
@@ -180,12 +179,10 @@ class BaseStatusTableViewCell: UITableViewCell {
     func updateUI(account: Account) {
         usernameLabel.text = "@\(account.acct)"
         avatarImageView.image = nil
-        avatarURL = account.avatar
-        ImageCache.avatars.get(account.avatar) { (data) in
-            guard let data = data, self.avatarURL == account.avatar else { return }
+        avatarRequest = ImageCache.avatars.get(account.avatar) { [weak self] (data) in
+            guard let self = self, let data = data, self.accountID == account.id else { return }
             DispatchQueue.main.async {
                 self.avatarImageView.image = UIImage(data: data)
-                self.avatarURL = nil
             }
         }
     }
@@ -200,9 +197,7 @@ class BaseStatusTableViewCell: UITableViewCell {
     override func prepareForReuse() {
         super.prepareForReuse()
         
-        if let avatarURL = avatarURL {
-            ImageCache.avatars.cancel(avatarURL)
-        }
+        avatarRequest?.cancel()
         attachmentsView.attachmentViews.allObjects.forEach { $0.removeFromSuperview() }
         showStatusAutomatically = false
     }

Tusker/Views/Status/TimelineStatusTableViewCell.swift

@@ -95,7 +95,7 @@ class TimelineStatusTableViewCell: BaseStatusTableViewCell {
     }
     
     func updateTimestamp() {
-        guard let status = mastodonController.cache.status(for: statusID) else { fatalError("Missing cached status \(statusID!)") }
+        guard let mastodonController = mastodonController, let status = mastodonController.cache.status(for: statusID) else { fatalError("Missing cached status \(statusID!)") }
         
         timestampLabel.text = status.createdAt.timeAgoString()
         timestampLabel.accessibilityLabel = TimelineStatusTableViewCell.relativeDateFormatter.localizedString(for: status.createdAt, relativeTo: Date())
@@ -236,8 +236,8 @@ extension TimelineStatusTableViewCell: TableViewSwipeActionProvider {
             completion(true)
             self.delegate?.showMoreOptions(forStatus: self.statusID, sourceView: self)
         }
-        more.image = UIImage(systemName: "ellipsis")
-        more.backgroundColor = .gray
+        more.image = UIImage(systemName: "ellipsis.circle.fill")
+        more.backgroundColor = .lightGray
         return UISwipeActionsConfiguration(actions: [reply, more])
     }