Another round of strict concurrency fixes

OpenInTusker/ActionViewController.swift

@@ -18,19 +18,23 @@ class ActionViewController: UIViewController {
         super.viewDidLoad()
         
         findURLFromWebPage { (components) in
-            if let components = components {
+            DispatchQueue.main.async {
+                if let components {
                     self.searchForURLInApp(components)
                 } else {
                     self.findURLItem { (components) in
-                    if let components = components {
+                        if let components {
+                            DispatchQueue.main.async {
                                 self.searchForURLInApp(components)
                             }
                         }
                     }
                 }
             }
+        }
+    }
     
-    private func findURLFromWebPage(completion: @escaping (URLComponents?) -> Void) {
+    private func findURLFromWebPage(completion: @escaping @Sendable (URLComponents?) -> Void) {
         for item in extensionContext!.inputItems as! [NSExtensionItem] {
             for provider in item.attachments! {
                 guard provider.hasItemConformingToTypeIdentifier(UTType.propertyList.identifier) else {
@@ -54,7 +58,7 @@ class ActionViewController: UIViewController {
         completion(nil)
     }
     
-    private func findURLItem(completion: @escaping (URLComponents?) -> Void) {
+    private func findURLItem(completion: @escaping @Sendable (URLComponents?) -> Void) {
         for item in extensionContext!.inputItems as! [NSExtensionItem] {
             for provider in item.attachments! {
                 guard provider.hasItemConformingToTypeIdentifier(UTType.url.identifier) else {

Packages/InstanceFeatures/Sources/InstanceFeatures/InstanceFeatures.swift

@@ -10,7 +10,7 @@ import Foundation
 import Combine
 import Pachyderm
 
-public class InstanceFeatures: ObservableObject {
+public final class InstanceFeatures: ObservableObject {
     private static let pleromaVersionRegex = try! NSRegularExpression(pattern: "\\(compatible; (pleroma|akkoma) (.*)\\)", options: .caseInsensitive)
     
     private let _featuresUpdated = PassthroughSubject<Void, Never>()

Packages/UserAccounts/Sources/UserAccounts/UserAccountInfo.swift

@@ -8,7 +8,7 @@
 import Foundation
 import CryptoKit
 
-public struct UserAccountInfo: Equatable, Hashable, Identifiable {
+public struct UserAccountInfo: Equatable, Hashable, Identifiable, Sendable {
     public let id: String
     public let instanceURL: URL
     public let clientID: String

ShareExtension/ShareMastodonContext.swift

@@ -12,7 +12,7 @@ import UserAccounts
 import InstanceFeatures
 import Combine
 
-class ShareMastodonContext: ComposeMastodonContext, ObservableObject {
+final class ShareMastodonContext: ComposeMastodonContext, ObservableObject, Sendable {
     let accountInfo: UserAccountInfo?
     let client: Client
     let instanceFeatures: InstanceFeatures
@@ -20,7 +20,9 @@ class ShareMastodonContext: ComposeMastodonContext, ObservableObject {
     @MainActor
     private var customEmojis: [Emoji]?
     
-    @Published var ownAccount: Account?
+    @MainActor
+    @Published
+    private(set) var ownAccount: Account?
     
     init(accountInfo: UserAccountInfo) {
         self.accountInfo = accountInfo

Tusker/API/MastodonController.swift

@@ -20,7 +20,7 @@ import OSLog
 private let oauthScopes = [Scope.read, .write, .follow]
 private let logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "MastodonController")
 
-class MastodonController: ObservableObject {
+final class MastodonController: ObservableObject, Sendable {
 
     @MainActor
     static private(set) var all = [UserAccountInfo: MastodonController]()
@@ -283,7 +283,8 @@ class MastodonController: ObservableObject {
                 let account = try await run(Client.getSelfAccount()).0
                 
                 let context = persistentContainer.viewContext
-                return await context.perform {
+                // this closure is declared separately so we can tell the compiler it's Sendable
+                let performBlock: @MainActor @Sendable () -> MainThreadBox<AccountMO> = {
                     let accountMO: AccountMO
                     if let existing = self.persistentContainer.account(for: account.id, in: context) {
                         accountMO = existing
@@ -296,6 +297,8 @@ class MastodonController: ObservableObject {
                     self.account = accountMO
                     return MainThreadBox(value: accountMO)
                 }
+                // it's safe to remove the MainActor annotation, because this is the view context
+                return await context.perform(unsafeBitCast(performBlock, to: (@Sendable () -> MainThreadBox<AccountMO>).self))
             }
             fetchOwnAccountTask = task
             return try await task.value.value
@@ -342,7 +345,7 @@ class MastodonController: ObservableObject {
         }
     }
     
-    private func retrying<T: Sendable>(_ label: StaticString, action: () async throws -> T) async throws -> T {
+    private func retrying<T: Sendable>(_ label: StaticString, action: @Sendable () async throws -> T) async throws -> T {
         for attempt in 0..<4 {
             do {
                 return try await action()
@@ -582,6 +585,7 @@ class MastodonController: ObservableObject {
         )
     }
     
+    @MainActor
     func createDraft(editing status: StatusMO, source: StatusSource) -> Draft {
         precondition(status.id == source.id)
         let draft = DraftsPersistentContainer.shared.createEditDraft(

Tusker/ImageGrayscalifier.swift

@@ -27,6 +27,18 @@ struct ImageGrayscalifier {
         }
     }
     
+    static func convertIfNecessary(url: URL?, image: UIImage) async -> UIImage? {
+        let grayscale = await MainActor.run {
+            Preferences.shared.grayscaleImages
+        }
+        if grayscale,
+           let source = image.cgImage {
+            return await convert(url: url, cgImage: source)
+        } else {
+            return image
+        }
+    }
+    
     static func convert(url: URL?, image: UIImage) -> UIImage? {
         if let url,
            let cached = cache.object(forKey: url as NSURL) {

Tusker/Screens/Explore/ExploreViewController.swift

@@ -14,7 +14,7 @@ import WebURLFoundationExtras
 
 class ExploreViewController: UIViewController, UICollectionViewDelegate, CollectionViewController {
 
-    weak var mastodonController: MastodonController!
+    private let mastodonController: MastodonController
     
     var collectionView: UICollectionView!
     private var dataSource: UICollectionViewDiffableDataSource<Section, Item>!

Tusker/Screens/Explore/ProfileDirectoryViewController.swift

@@ -11,7 +11,7 @@ import Pachyderm
 
 class ProfileDirectoryViewController: UIViewController {
 
-    weak var mastodonController: MastodonController!
+    private let mastodonController: MastodonController
     
     private var collectionView: UICollectionView!
     private var dataSource: UICollectionViewDiffableDataSource<Section, Item>!

Tusker/Screens/Explore/SuggestedProfilesViewController.swift

@@ -11,7 +11,7 @@ import Pachyderm
 
 class SuggestedProfilesViewController: UIViewController, CollectionViewController {
     
-    weak var mastodonController: MastodonController!
+    private let mastodonController: MastodonController
     
     var collectionView: UICollectionView!
     private var layout: MultiColumnCollectionViewLayout!

Tusker/Screens/Explore/TrendingHashtagsViewController.swift

@@ -13,7 +13,7 @@ import Combine
 
 class TrendingHashtagsViewController: UIViewController {
 
-    weak var mastodonController: MastodonController!
+    private let mastodonController: MastodonController
     
     private var collectionView: UICollectionView!
     private var dataSource: UICollectionViewDiffableDataSource<Section, Item>!

Tusker/Screens/Explore/TrendingLinksViewController.swift

@@ -14,7 +14,7 @@ import Combine
 
 class TrendingLinksViewController: UIViewController, CollectionViewController {
     
-    weak var mastodonController: MastodonController!
+    private let mastodonController: MastodonController
     
     var collectionView: UICollectionView!
     private var dataSource: UICollectionViewDiffableDataSource<Section, Item>!

Tusker/Screens/Explore/TrendingStatusesViewController.swift

@@ -11,7 +11,7 @@ import Pachyderm
 
 class TrendingStatusesViewController: UIViewController, CollectionViewController {
     
-    weak var mastodonController: MastodonController!
+    private let mastodonController: MastodonController
     let filterer: Filterer
     
     var collectionView: UICollectionView! {

Tusker/Screens/Large Image/LargeImageViewController.swift

@@ -144,7 +144,9 @@ class LargeImageViewController: UIViewController, UIScrollViewDelegate, LargeIma
             contentViewTopConstraint,
         ])
         contentViewSizeObservation = (contentView as UIView).observe(\.bounds, changeHandler: { [unowned self] _, _ in
+            MainActor.runUnsafely {
                 self.centerImage()
+            }
         })
     }
     

Tusker/Screens/Main/MainSplitViewController.swift

@@ -11,7 +11,7 @@ import Combine
 
 class MainSplitViewController: UISplitViewController {
 
-    weak var mastodonController: MastodonController!
+    private let mastodonController: MastodonController
     
     private var sidebar: MainSidebarViewController!
     private var fastAccountSwitcher: FastAccountSwitcherViewController?

Tusker/Screens/Main/MainTabBarViewController.swift

@@ -11,7 +11,7 @@ import ComposeUI
 
 class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
     
-    weak var mastodonController: MastodonController!
+    private let mastodonController: MastodonController
     
     private var composePlaceholder: UIViewController!
     

Tusker/Screens/Notifications/NotificationsCollectionViewController.swift

@@ -15,7 +15,7 @@ import Sentry
 
 class NotificationsCollectionViewController: UIViewController, TimelineLikeCollectionViewController, CollectionViewController {
     
-    weak var mastodonController: MastodonController!
+    private let mastodonController: MastodonController
     private let filterer: Filterer
     
     private let allowedTypes: [Pachyderm.Notification.Kind]

Tusker/Screens/Onboarding/InstanceSelectorTableViewController.swift

@@ -27,7 +27,7 @@ class InstanceSelectorTableViewController: UITableViewController {
     
     weak var delegate: InstanceSelectorTableViewControllerDelegate?
 
-    var dataSource: DataSource!
+    var dataSource: UITableViewDiffableDataSource<Section, Item>!
     var searchController: UISearchController!
     
     var recommendedInstances: [InstanceSelector.Instance] = []
@@ -73,7 +73,7 @@ class InstanceSelectorTableViewController: UITableViewController {
         tableView.estimatedRowHeight = 120
         createActivityIndicatorHeader()
         
-        dataSource = DataSource(tableView: tableView, cellProvider: { (tableView, indexPath, item) -> UITableViewCell? in
+        dataSource = UITableViewDiffableDataSource(tableView: tableView, cellProvider: { (tableView, indexPath, item) -> UITableViewCell? in
             switch item {
             case let .selected(_, instance):
                 let cell = tableView.dequeueReusableCell(withIdentifier: instanceCell, for: indexPath) as! InstanceTableViewCell
@@ -338,9 +338,6 @@ extension InstanceSelectorTableViewController {
             }
         }
     }
-    class DataSource: UITableViewDiffableDataSource<Section, Item> {
-        
-    }
 }
 
 extension InstanceSelectorTableViewController: UISearchResultsUpdating {

Tusker/Screens/Profile/ProfileViewController.swift

@@ -12,7 +12,7 @@ import Combine
 
 class ProfileViewController: UIViewController, StateRestorableViewController {
     
-    weak var mastodonController: MastodonController!
+    let mastodonController: MastodonController
     
     // This property is optional because MyProfileViewController may not have the user's account ID
     // when first constructed. It should never be set to nil.

Tusker/Screens/Report/ReportStatusView.swift

@@ -8,6 +8,7 @@
 
 import SwiftUI
 
+@MainActor
 private var converter = HTMLConverter(
     font: .preferredFont(forTextStyle: .body),
     monospaceFont: UIFontMetrics.default.scaledFont(for: .monospacedSystemFont(ofSize: 17, weight: .regular)),
@@ -15,6 +16,7 @@ private var converter = HTMLConverter(
     paragraphStyle: .default
 )
 
+@MainActor
 struct ReportStatusView: View {
     let status: StatusMO
     let mastodonController: MastodonController

Tusker/Screens/Search/SearchResultsViewController.swift

@@ -30,7 +30,7 @@ extension SearchResultsViewControllerDelegate {
 
 class SearchResultsViewController: UIViewController, CollectionViewController {
 
-    weak var mastodonController: MastodonController!
+    let mastodonController: MastodonController
     
     weak var exploreNavigationController: UINavigationController?
     weak var delegate: SearchResultsViewControllerDelegate?

Tusker/Screens/Timeline/TimelineViewController.swift

@@ -32,7 +32,7 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
     weak var delegate: TimelineViewControllerDelegate?
     
     let timeline: Timeline
-    weak var mastodonController: MastodonController!
+    let mastodonController: MastodonController
     private let filterer: Filterer
     
     var persistsState = false
@@ -587,7 +587,7 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
             snapshot.appendSections([.statuses])
             let items = allStatuses.map { Item.status(id: $0.id, collapseState: .unknown, filterState: .unknown) }
             snapshot.appendItems(items)
-            await dataSource.apply(snapshot, animatingDifferences: false)
+            await apply(snapshot, animatingDifferences: false)
             collectionView.contentOffset = CGPoint(x: 0, y: -collectionView.adjustedContentInset.top)
             
             stateRestorationLogger.debug("TimelineViewController: restored from timeline marker with last read ID: \(home.lastReadID)")

Tusker/Views/Account Detail/LargeAccountDetailView.swift

@@ -73,8 +73,8 @@ class LargeAccountDetailView: UIView {
         if let avatar = account.avatar {
             avatarRequest = ImageCache.avatars.get(avatar) { [weak self] (_, image) in
                 guard let self = self, let image = image else { return }
-                self.avatarRequest = nil
                 DispatchQueue.main.async {
+                    self.avatarRequest = nil
                     self.avatarImageView.image = image
                 }
             }

Tusker/Views/CachedImageView.swift

@@ -90,8 +90,7 @@ class CachedImageView: UIImageView {
                 return
             }
             try Task.checkCancellation()
-            // TODO: check that this isn't on the main thread
+            guard let transformedImage = await ImageGrayscalifier.convertIfNecessary(url: url, image: image) else {
-            guard let transformedImage = ImageGrayscalifier.convertIfNecessary(url: url, image: image) else {
                 return
             }
             try Task.checkCancellation()

Tusker/Views/Instance Cell/InstanceTableViewCell.swift

@@ -19,8 +19,11 @@ class InstanceTableViewCell: UITableViewCell {
     var instance: InstanceV1?
     var selectorInstance: InstanceSelector.Instance?
     
-    var thumbnailURL: URL?
+    private var thumbnailTask: Task<Void, Never>?
-    var thumbnailRequest: ImageCache.Request?
+    
+    deinit {
+        thumbnailTask?.cancel()
+    }
     
     override func awakeFromNib() {
         super.awakeFromNib()
@@ -68,20 +71,19 @@ class InstanceTableViewCell: UITableViewCell {
     
     private func updateThumbnail(url: URL) {
         thumbnailImageView.image = nil
-        thumbnailURL = url
+        thumbnailTask = Task {
-        thumbnailRequest = ImageCache.attachments.get(url) { [weak self] (_, image) in
+            guard let image = await ImageCache.attachments.get(url).1,
-            guard let self = self, self.thumbnailURL == url, let image = image else { return }
+                  !Task.isCancelled else {
-            self.thumbnailRequest = nil
+                return
-            DispatchQueue.main.async {
-                self.thumbnailImageView.image = image
             }
+            thumbnailImageView.image = image
         }
     }
     
     override func prepareForReuse() {
         super.prepareForReuse()
         
-        thumbnailRequest?.cancel()
+        thumbnailTask?.cancel()
         instance = nil
         selectorInstance = nil
     }

Tusker/Views/MultiSourceEmojiLabel.swift

@@ -24,7 +24,7 @@ class MultiSourceEmojiLabel: UILabel, BaseEmojiLabel {
         
         var attributedStrings = pairs.map { NSAttributedString(string: $0.0) }
         
-        let recombine = { [weak self] in
+        let recombine: @MainActor @Sendable () -> Void = { [weak self] in
             if let self,
                let combiner = self.combiner {
                 self.attributedText = combiner(attributedStrings)

Tusker/Views/Profile Header/ProfileFieldsView.swift

@@ -53,7 +53,9 @@ class ProfileFieldsView: UIView {
     
     private func commonInit() {
         boundsObservation = observe(\.bounds, changeHandler: { [unowned self] _, _ in
+            MainActor.runUnsafely {
                 self.setNeedsUpdateConstraints()
+            }
         })
         
         #if os(visionOS)

Tusker/Views/Profile Header/ProfileHeaderView.swift

@@ -42,8 +42,7 @@ class ProfileHeaderView: UIView {
     
     var accountID: String!
     
-    private var avatarRequest: ImageCache.Request?
+    private var imagesTask: Task<Void, Never>?
-    private var headerRequest: ImageCache.Request?
     
     private var isGrayscale = false
     private var followButtonMode = FollowButtonMode.follow {
@@ -56,8 +55,7 @@ class ProfileHeaderView: UIView {
     }
     
     deinit {
-        avatarRequest?.cancel()
+        imagesTask?.cancel()
-        headerRequest?.cancel()
     }
     
     override func awakeFromNib() {
@@ -134,7 +132,12 @@ class ProfileHeaderView: UIView {
         usernameLabel.text = "@\(account.acct)"
         lockImageView.isHidden = !account.locked
         
-        updateImages(account: account)
+        imagesTask?.cancel()
+        let avatar = account.avatar
+        let header = account.header
+        imagesTask = Task {
+            await updateImages(avatar: avatar, header: header)
+        }
         
         moreButton.menu = UIMenu(title: "", image: nil, identifier: nil, options: [], children: delegate?.actionsForProfile(accountID: accountID, source: .view(moreButton), fetchRelationship: false) ?? [])
         
@@ -286,50 +289,41 @@ class ProfileHeaderView: UIView {
         displayNameLabel.updateForAccountDisplayName(account: account)
         
         if isGrayscale != Preferences.shared.grayscaleImages {
-            updateImages(account: account)
-        }
-    }
-    
-    private func updateImages(account: AccountMO) {
             isGrayscale = Preferences.shared.grayscaleImages
-        
+            imagesTask?.cancel()
-        let accountID = account.id
+            let avatar = account.avatar
-        if let avatarURL = account.avatar {
+            let header = account.header
-            // always load original for avatars, because ImageCache.avatars stores them scaled-down in memory
+            imagesTask = Task {
-            avatarRequest = ImageCache.avatars.get(avatarURL, loadOriginal: true) { [weak self] (_, image) in
+                await updateImages(avatar: avatar, header: header)
-                guard let self = self,
-                      let image = image,
-                      self.accountID == accountID,
-                      let transformedImage = ImageGrayscalifier.convertIfNecessary(url: avatarURL, image: image) else {
-                    DispatchQueue.main.async {
-                        self?.avatarRequest = nil
             }
+        }
+    }
+    
+    private nonisolated func updateImages(avatar: URL?, header: URL?) async {
+        await withTaskGroup(of: Void.self) { group in
+            group.addTask {
+                guard let avatar,
+                      let image = await ImageCache.avatars.get(avatar, loadOriginal: true).1,
+                      let transformedImage = await ImageGrayscalifier.convertIfNecessary(url: avatar, image: image),
+                      !Task.isCancelled else {
                     return
                 }
-                
+                await MainActor.run {
-                DispatchQueue.main.async {
-                    self.avatarRequest = nil
                     self.avatarImageView.image = transformedImage
                 }
             }
-        }
+            group.addTask {
-        if let header = account.header {
+                guard let header,
-            headerRequest = ImageCache.headers.get(header) { [weak self] (_, image) in
+                      let image = await ImageCache.avatars.get(header, loadOriginal: true).1,
-                guard let self = self,
+                      let transformedImage = await ImageGrayscalifier.convertIfNecessary(url: header, image: image),
-                      let image = image,
+                      !Task.isCancelled else {
-                      self.accountID == accountID,
-                      let transformedImage = ImageGrayscalifier.convertIfNecessary(url: header, image: image) else {
-                    DispatchQueue.main.async {
-                        self?.headerRequest = nil
-                    }
                     return
                 }
-                
+                await MainActor.run {
-                DispatchQueue.main.async {
-                    self.headerRequest = nil
                     self.headerImageView.image = transformedImage
                 }
             }
+            await group.waitForAll()
         }
     }