Add an ItemAt method to get the object at the indexPath

Author: Todd Berman

ReactiveUI.Platforms/Cocoa/ReactiveCollectionViewSource.cs

@@ -135,6 +135,11 @@ public override void ItemSelected(UICollectionView collectionView, NSIndexPath i
             elementSelected.OnNext(commonSource.ItemAt(indexPath));
         }
 
+        public object ItemAt(NSIndexPath indexPath)
+        {
+            return commonSource.ItemAt(indexPath);
+        }
+
         protected override void Dispose(bool disposing)
         {
             if (disposing) commonSource.Dispose();

ReactiveUI.Platforms/Cocoa/ReactiveTableViewSource.cs

@@ -224,7 +224,10 @@ public override UIView GetViewForFooter(UITableView tableView, int section)
             return footer == null ? null : footer.View.Invoke();
         }
 
-
+        public object ItemAt(NSIndexPath indexPath)
+        {
+            return commonSource.ItemAt(indexPath);
+        }
 
         // Boring copy-paste of ReactiveObject et al follows:
         [field:IgnoreDataMember]