Fix crash when opening profile view controller with uncached account

E.g., by tapping a mention in a status

Tusker/CoreData/MastodonCachePersistentStore.swift

@@ -147,19 +147,20 @@ class MastodonCachePersistentStore: NSPersistentContainer {
     }
     
     @discardableResult
-    private func upsert(account: Account) -> AccountMO {
-        if let accountMO = self.account(for: account.id, in: self.backgroundContext) {
+    private func upsert(account: Account, in context: NSManagedObjectContext) -> AccountMO {
+        if let accountMO = self.account(for: account.id, in: context) {
             accountMO.updateFrom(apiAccount: account, container: self)
             return accountMO
         } else {
-            return AccountMO(apiAccount: account, container: self, context: self.backgroundContext)
+            return AccountMO(apiAccount: account, container: self, context: context)
         }
     }
     
-    func addOrUpdate(account: Account, completion: ((AccountMO) -> Void)? = nil) {
-        backgroundContext.perform {
-            let accountMO = self.upsert(account: account)
-            self.save(context: self.backgroundContext)
+    func addOrUpdate(account: Account, in context: NSManagedObjectContext? = nil, completion: ((AccountMO) -> Void)? = nil) {
+        let context = context ?? backgroundContext
+        context.perform {
+            let accountMO = self.upsert(account: account, in: context)
+            self.save(context: context)
             completion?(accountMO)
             self.accountSubject.send(account.id)
         }
@@ -199,7 +200,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
     
     func addAll(accounts: [Account], completion: (() -> Void)? = nil) {
         backgroundContext.perform {
-            accounts.forEach { self.upsert(account: $0) }
+            accounts.forEach { self.upsert(account: $0, in: self.backgroundContext) }
             self.save(context: self.backgroundContext)
             completion?()
             accounts.forEach { self.accountSubject.send($0.id) }
@@ -213,7 +214,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
             // since the status has the same account as the notification
             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) }
+            accounts.forEach { self.upsert(account: $0, in: self.backgroundContext) }
             self.save(context: self.backgroundContext)
             completion?()
             statuses.forEach { self.statusSubject.send($0.id) }
@@ -227,7 +228,7 @@ class MastodonCachePersistentStore: NSPersistentContainer {
             var updatedStatuses = [String]()
             
             block(self.backgroundContext, { (accounts) in
-                accounts.forEach { self.upsert(account: $0) }
+                accounts.forEach { self.upsert(account: $0, in: self.backgroundContext) }
                 updatedAccounts.append(contentsOf: accounts.map { $0.id })
             }, { (statuses) in
                 statuses.forEach { self.upsert(status: $0, context: self.backgroundContext) }

Tusker/Screens/Profile/ProfileStatusesViewController.swift

@@ -29,9 +29,10 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
         view as! UICollectionView
     }
     private(set) var dataSource: UICollectionViewDiffableDataSource<Section, Item>!
-    
     private(set) var headerCell: ProfileHeaderCollectionViewCell?
     
+    private var state: State = .unloaded
+    
     init(accountID: String?, kind: Kind, owner: ProfileViewController) {
         self.accountID = accountID
         self.kind = kind
@@ -92,9 +93,18 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
             .receive(on: DispatchQueue.main)
             .filter { [unowned self] in $0 == self.accountID }
             .sink { [unowned self] id in
-                var snapshot = dataSource.snapshot()
-                snapshot.reconfigureItems([.header(id)])
-                dataSource.apply(snapshot, animatingDifferences: true)
+                switch state {
+                case .unloaded:
+                    Task {
+                        await load()
+                    }
+                case .loading:
+                    break
+                case .loaded, .addedHeader:
+                    var snapshot = dataSource.snapshot()
+                    snapshot.reconfigureItems([.header(id)])
+                    dataSource.apply(snapshot, animatingDifferences: true)
+                }
             }
             .store(in: &cancellables)
     }
@@ -159,20 +169,26 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
     }
     
     private func load() async {
-        guard accountID != nil,
-              await controller.state == .notLoadedInitial,
-              isViewLoaded else {
+        guard isViewLoaded,
+              let accountID,
+              case .unloaded = state,
+              mastodonController.persistentContainer.account(for: accountID) != nil else {
             return
         }
         
+        state = .loading
+        
         var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
         snapshot.appendSections([.header, .pinned, .statuses])
         snapshot.appendItems([.header(accountID)], toSection: .header)
         await apply(snapshot, animatingDifferences: false)
-        print("added header item")
+        
+        state = .addedHeader
         
         await controller.loadInitial()
         await tryLoadPinned()
+        
+        state = .loaded
     }
     
     private func tryLoadPinned() async {
@@ -222,6 +238,15 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
     
 }
 
+extension ProfileStatusesViewController {
+    enum State {
+        case unloaded
+        case loading
+        case addedHeader
+        case loaded
+    }
+}
+
 extension ProfileStatusesViewController {
     enum Kind {
         case statuses, withReplies, onlyMedia

Tusker/Screens/Profile/ProfileViewController.swift

@@ -116,7 +116,7 @@ class ProfileViewController: UIPageViewController {
                 let req = Client.getAccount(id: accountID)
                 let (account, _) = try await mastodonController.run(req)
                 let mo = await withCheckedContinuation { continuation in
-                    mastodonController.persistentContainer.addOrUpdate(account: account) { (mo) in
+                    mastodonController.persistentContainer.addOrUpdate(account: account, in: mastodonController.persistentContainer.viewContext) { (mo) in
                         continuation.resume(returning: mo)
                     }
                 }