🐛 Improve "scroll to me" (#1482)

* 🐛 Fix immediate scroll functionality in LeaderboardPage

* Cleanup

* Resolve comments

Author: zacharykeeping

src/MobileUI/Features/Leaderboard/LeaderboardPage.xaml.cs

@@ -1,6 +1,4 @@
-using Microsoft.Maui.Controls.Internals;
-
-namespace SSW.Rewards.Mobile.Pages;
+namespace SSW.Rewards.Mobile.Pages;
 
 public partial class LeaderboardPage
 {
@@ -23,14 +21,21 @@ protected override async void OnAppearing()
         base.OnAppearing();
         _firebaseAnalyticsService.Log("LeaderboardPage");
 
+        _viewModel.ScrollTo += ScrollTo;
+
         // Page might be ready a bit earlier due to cached leaderboard
         // while data is refreshed in the background.
         _viewModel.ReadyEarly += Animate;
         await _viewModel.Initialise();
 
         await Animate();
+    }
 
-        _viewModel.ScrollTo += ScrollTo;
+    protected override void OnDisappearing()
+    {
+        base.OnDisappearing();
+        _viewModel.ScrollTo -= ScrollTo;
+        _viewModel.ReadyEarly -= Animate;
     }
 
     private void ScrollTo(int i)

src/MobileUI/Features/Leaderboard/LeaderboardViewModel.cs

@@ -15,6 +15,7 @@ public partial class LeaderboardViewModel : BaseViewModel
     private bool _loaded;
 
     private const int PageSize = 50;
+    private const int ScrollDelayMilliseconds = 50;
     private int _page;
     private bool _limitReached;
 
@@ -153,25 +154,27 @@ await _fileCacheService.FetchAndRefresh(
                 LeaderViewModel myCard = Leaders.FirstOrDefault(l => l.IsMe);
                 while (myCard == null)
                 {
-                    myCard = Leaders.FirstOrDefault(l => l.IsMe);
-
-                    if (myCard != null)
+                    if (_limitReached)
                     {
-                        continue;
+                        break;
                     }
 
                     ++_page;
 
                     var result = await FetchLeaderboard(CurrentPeriod, _page, PageSize);
                     ProcessLeaders(result);
 
-                    if (_limitReached)
-                    {
-                        break;
-                    }
+                    myCard = Leaders.FirstOrDefault(l => l.IsMe);
                 }
 
-                ScrollToCard(myCard);
+                if (myCard != null)
+                {
+                    await MainThread.InvokeOnMainThreadAsync(async () =>
+                    {
+                        await Task.Delay(ScrollDelayMilliseconds);
+                        ScrollToCard(myCard);
+                    });
+                }
             }
             else
             {