Workaround receiving events with Shell on iPhone

Fixes: #3

Author: jeremy-visionaid

src/Plugin.Maui.KeyListener/KeyboardPageViewController.cs

@@ -13,6 +13,17 @@ public class KeyboardPageViewController : PageViewController
 		internal KeyboardPageViewController(IView page, IMauiContext mauiContext)
 			: base(page, mauiContext) { }
 
+#if IOS // Workaround to allow receiving keys when the root page is a Shell
+		public override bool CanBecomeFirstResponder => true;
+
+		public override void ViewIsAppearing(bool animated)
+		{
+			base.ViewIsAppearing(animated);
+
+			BecomeFirstResponder();
+		}
+#endif
+
 		public override void PressesBegan(NSSet<UIPress> presses, UIPressesEvent evt)
 		{
 			if (ProcessPresses(presses, evt, false))