Add managed UIKit iOS client

clients/apple/dotnet/VoiceCat.iOS/UiHelpers.cs

@@ -0,0 +1,20 @@
+using UIKit;
+
+namespace VoiceCat.iOS;
+
+internal static class UiHelpers
+{
+    internal static void ShowError(UIViewController owner, Exception exception) => ShowMessage(owner, "VoiceCat", exception.Message);
+    internal static void ShowMessage(UIViewController owner, string title, string message)
+    {
+        UIAlertController alert = UIAlertController.Create(title, message, UIAlertControllerStyle.Alert);
+        alert.AddAction(UIAlertAction.Create("OK", UIAlertActionStyle.Default, null)); owner.PresentViewController(alert, true, null);
+    }
+
+    internal static UITextField Field(string placeholder, bool secure = false)
+    {
+        var field = new UITextField { Placeholder = placeholder, BorderStyle = UITextBorderStyle.RoundedRect,
+            SecureTextEntry = secure, TranslatesAutoresizingMaskIntoConstraints = false };
+        field.AccessibilityLabel = placeholder; return field;
+    }
+}