Also perform jump to present check when the timeline VC reappears onscreen

Tusker/Screens/Timeline/TimelineViewController.swift

@@ -25,6 +25,8 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
     
     private var contentOffsetObservation: NSKeyValueObservation?
     private var activityToRestore: NSUserActivity?
+    // the last time this VC disappeared or the scene was backgrounded while it was active, used to decide if we want to check for present when reappearing
+    private var disappearedAt: Date?
     
     init(for timeline: Timeline, mastodonController: MastodonController!) {
         self.timeline = timeline
@@ -115,6 +117,7 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
         }
         
         NotificationCenter.default.addObserver(self, selector: #selector(sceneWillEnterForeground), name: UIScene.willEnterForegroundNotification, object: nil)
+        NotificationCenter.default.addObserver(self, selector: #selector(sceneDidEnterBackground), name: UIScene.didEnterBackgroundNotification, object: nil)
     }
     
     // separate method because InstanceTimelineViewController needs to be able to customize it
@@ -199,6 +202,8 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
                     await controller.loadInitial()
                 }
             }
+        } else {
+            checkPresentIfEnoughTimeElapsed()
         }
     }
     
@@ -215,6 +220,12 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
         }
     }
     
+    override func viewDidDisappear(_ animated: Bool) {
+        super.viewDidDisappear(animated)
+        
+        disappearedAt = Date()
+    }
+    
     func stateRestorationActivity() -> NSUserActivity? {
         guard isViewLoaded else {
             return nil
@@ -376,9 +387,16 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
               view.window?.windowScene == scene else {
             return
         }
-        Task {
+        checkPresentIfEnoughTimeElapsed()
-            await checkPresent(jumpImmediately: false)
+    }
+    
+    @objc private func sceneDidEnterBackground(_ notification: Foundation.Notification) {
+        guard let scene = notification.object as? UIScene,
+              // view.window is nil when the VC is not on screen
+              view.window?.windowScene == scene else {
+            return
         }
+        disappearedAt = Date()
     }
     
     @objc func refresh() {
@@ -406,6 +424,17 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
         }
     }
     
+    private func checkPresentIfEnoughTimeElapsed() {
+        guard let disappearedAt,
+              -disappearedAt.timeIntervalSinceNow > 60 * 60 /* 1 hour */ else {
+            return
+        }
+        self.disappearedAt = nil
+        Task {
+            await checkPresent(jumpImmediately: false)
+        }
+    }
+    
     func checkPresent(jumpImmediately: Bool) async {
         if case .idle = controller.state,
            let presentItems = try? await loadInitial(),