Fix iOS voice capture and screen sharing

clients/apple/VoiceCat.iOS/BroadcastAudioPump.cs

@@ -9,7 +9,7 @@ internal sealed class BroadcastAudioPump : IAsyncDisposable
     private const uint Magic = 0x56434252, Version = 1;
     private const int Header = 64, Capacity = 96_000, Frame = 960;
     private readonly CancellationTokenSource stop = new();
-    private Task worker = Task.CompletedTask;
+    private Thread? worker;
     private VoiceCatClient? client;
     private uint streamId;
     private bool active;
@@ -19,15 +19,21 @@ internal sealed class BroadcastAudioPump : IAsyncDisposable
     internal event Action? Changed;
     internal bool IsActive => active;
 
-    internal void Start(VoiceCatClient owner) { client = owner; worker = RunAsync(stop.Token); }
-
-    private async Task RunAsync(CancellationToken token)
+    internal void Start(VoiceCatClient owner)
     {
+        client = owner;
+        worker = new Thread(Run) { IsBackground = true, Name = "VoiceCat iOS screen audio", Priority = ThreadPriority.AboveNormal };
+        worker.Start();
+    }
+
+    private void Run()
+    {
+        CancellationToken token = stop.Token;
         while (!token.IsCancellationRequested)
         {
-            try { await DrainAsync(token); }
-            catch (Exception exception) when (exception is IOException or UnauthorizedAccessException or InvalidDataException) { }
-            await Task.Delay(10, token).ConfigureAwait(false);
+            try { DrainAsync(token).GetAwaiter().GetResult(); }
+            catch (Exception exception) when (exception is IOException or UnauthorizedAccessException or InvalidDataException or OperationCanceledException) { }
+            if (!token.IsCancellationRequested) Thread.Sleep(5);
         }
     }
 
@@ -78,8 +84,9 @@ internal sealed class BroadcastAudioPump : IAsyncDisposable
 
     private void SetActive(bool value) { if (active == value) return; active = value; Changed?.Invoke(); }
 
-    public async ValueTask DisposeAsync()
+    public ValueTask DisposeAsync()
     {
-        stop.Cancel(); Interlocked.Increment(ref generation); try { await worker.ConfigureAwait(false); } catch (OperationCanceledException) { } StopStream(); SetActive(false); stop.Dispose();
+        stop.Cancel(); Interlocked.Increment(ref generation); worker?.Join(); worker = null;
+        StopStream(); SetActive(false); stop.Dispose(); return ValueTask.CompletedTask;
     }
 }