More comments.

Author: SebastianStehle

sdk/Notifo.SDK/NotifoMobilePush/NotifoMobilePushImplementation.ios.cs

@@ -52,6 +52,7 @@ public async Task DidReceivePullRefreshRequestAsync(PullRefreshOptions? options
         {
             options ??= new PullRefreshOptions();
 
+            // iOS does not maintain a queue of undelivered notifications, therefore we have to query here.
             var notifications = await GetPendingNotificationsAsync(options.Take, options.Period);
 
             foreach (var notification in notifications)
@@ -89,6 +90,7 @@ private async Task<IEnumerable<UserNotificationDto>> GetPendingNotificationsAsyn
                 var currentSeen = await GetSeenNotificationsAsync();
                 var currentTime = DateTimeOffset.UtcNow;
 
+                // Only take the recent notifications into account (default: 3 days).
                 bool IsRecent(DateTimeOffset date)
                 {
                     return (currentTime - date.UtcDateTime) <= maxAge;

sdk/Notifo.SDK/NotifoMobilePush/NotifoMobilePushImplementation.tracking.cs

@@ -53,13 +53,15 @@ public async Task TrackNotificationsAsync(params Guid[] ids)
             {
                 var set = await LoadSeenNotificationsAsync();
 
+                // Store the seen notifications immediately as a cache, if the actual command to the server fails.
                 await seenNotificationsStore.AddSeenNotificationIdsAsync(Capacity, ids);
 
                 foreach (var id in ids)
                 {
                     set.Add(id, Capacity);
                 }
 
+                // Track all notifications with one HTTP request.
                 commandQueue.Run(new TrackSeenCommand { Ids = ids.ToHashSet(), Token = token });
             }
             catch (Exception ex)
@@ -75,12 +77,8 @@ public async Task TrackNotificationsAsync(params Guid[] ids)
 
         private async Task<SlidingSet<Guid>> LoadSeenNotificationsAsync()
         {
-            if (seenNotifications == null)
-            {
-                seenNotifications = await seenNotificationsStore.GetSeenNotificationIdsAsync();
-            }
-
-            return seenNotifications;
+            // Only query the notifications once and then hold everything in-memory.
+            return seenNotifications ??= await seenNotificationsStore.GetSeenNotificationIdsAsync();
         }
     }
 }