Workaround for follow menu item never resolving on macOS

See #198

Tusker/CoreData/MastodonCachePersistentStore.swift

@@ -179,20 +179,21 @@ class MastodonCachePersistentStore: NSPersistentContainer {
     }
     
     @discardableResult
-    private func upsert(relationship: Relationship) -> RelationshipMO {
-        if let relationshipMO = self.relationship(forAccount: relationship.id, in: self.backgroundContext) {
+    private func upsert(relationship: Relationship, in context: NSManagedObjectContext) -> RelationshipMO {
+        if let relationshipMO = self.relationship(forAccount: relationship.id, in: context) {
             relationshipMO.updateFrom(apiRelationship: relationship, container: self)
             return relationshipMO
         } else {
-            let relationshipMO = RelationshipMO(apiRelationship: relationship, container: self, context: self.backgroundContext)
+            let relationshipMO = RelationshipMO(apiRelationship: relationship, container: self, context: context)
             return relationshipMO
         }
     }
     
-    func addOrUpdate(relationship: Relationship, completion: ((RelationshipMO) -> Void)? = nil) {
-        backgroundContext.perform {
-            let relationshipMO = self.upsert(relationship: relationship)
-            self.save(context: self.backgroundContext)
+    func addOrUpdate(relationship: Relationship, in context: NSManagedObjectContext? = nil, completion: ((RelationshipMO) -> Void)? = nil) {
+        let context = context ?? backgroundContext
+        context.perform {
+            let relationshipMO = self.upsert(relationship: relationship, in: context)
+            self.save(context: context)
             completion?(relationshipMO)
             self.relationshipSubject.send(relationship.id)
         }

Tusker/Screens/Utilities/Previewing.swift

@@ -60,14 +60,25 @@ extension MenuActionProvider {
                 draft.visibility = .direct
                 self.navigationDelegate?.compose(editing: draft)
             }),
-            UIDeferredMenuElement.uncached({ (elementHandler) in
+            UIDeferredMenuElement.uncached({ @MainActor elementHandler in
+                let relationship = Task {
+                    await self.fetchRelationship(accountID: accountID, mastodonController: mastodonController)
+                }
+                // workaround for #198, may result in showing outdated relationship, so only do so where necessary
+                if ProcessInfo.processInfo.isiOSAppOnMac,
+                    let mo = mastodonController.persistentContainer.relationship(forAccount: accountID),
+                   let action = self.followAction(for: mo, mastodonController: mastodonController) {
+                    elementHandler([action])
+                } else {
                     Task { @MainActor in
-                    if let action = await self.followAction(for: accountID, mastodonController: mastodonController) {
+                        if let relationship = await relationship.value,
+                           let action = self.followAction(for: relationship, mastodonController: mastodonController) {
                             elementHandler([action])
                         } else {
                             elementHandler([])
                         }
                     }
+                }
             })
         ]
         
@@ -381,16 +392,26 @@ extension MenuActionProvider {
         })
     }
     
-    private func followAction(for accountID: String, mastodonController: MastodonController) async -> UIMenuElement? {
-        guard let ownAccount = try? await mastodonController.getOwnAccount(),
-              accountID != ownAccount.id else {
+    private func fetchRelationship(accountID: String, mastodonController: MastodonController) async -> RelationshipMO? {
+        let req = Client.getRelationships(accounts: [accountID])
+        guard let (relationships, _) = try? await mastodonController.run(req),
+              let r = relationships.first else {
             return nil
         }
-        let request = Client.getRelationships(accounts: [accountID])
-        guard let (relationships, _) = try? await mastodonController.run(request),
-              let relationship = relationships.first else {
+        return await withCheckedContinuation { continuation in
+            mastodonController.persistentContainer.addOrUpdate(relationship: r, in: mastodonController.persistentContainer.viewContext) { mo in
+                continuation.resume(returning: mo)
+            }
+        }
+    }
+    
+    @MainActor
+    private func followAction(for relationship: RelationshipMO, mastodonController: MastodonController) -> UIMenuElement? {
+        guard let ownAccount = mastodonController.account,
+              relationship.accountID != ownAccount.id else {
             return nil
         }
+        let accountID = relationship.accountID
         let following = relationship.following
         return createAction(identifier: "follow", title: following ? "Unfollow" : "Follow", systemImageName: following ? "person.badge.minus" : "person.badge.plus") { _ in
             let request = (following ? Account.unfollow : Account.follow)(accountID)