feat: complete UM Trace iOS and field UI integration

FieldLogger/Views/Controls/AppStatusBar.xaml.cs

@@ -0,0 +1,40 @@
+using FieldLogger.ViewModels;
+
+namespace FieldLogger.Views.Controls;
+
+public partial class AppStatusBar : ContentView
+{
+    private IDispatcherTimer? _staleTimer;
+
+    public AppStatusBar()
+    {
+        InitializeComponent();
+    }
+
+    protected override void OnHandlerChanged()
+    {
+        base.OnHandlerChanged();
+
+        if (Handler is null)
+        {
+            _staleTimer?.Stop();
+            _staleTimer = null;
+            return;
+        }
+
+        if (_staleTimer is not null)
+            return;
+
+        _staleTimer = Dispatcher.CreateTimer();
+        _staleTimer.Interval = TimeSpan.FromSeconds(1);
+        _staleTimer.Tick += (_, _) => (BindingContext as AppStatusViewModel)?.Refresh();
+        _staleTimer.Start();
+        (BindingContext as AppStatusViewModel)?.Refresh();
+    }
+
+    protected override void OnBindingContextChanged()
+    {
+        base.OnBindingContextChanged();
+        (BindingContext as AppStatusViewModel)?.Refresh();
+    }
+}