Fix possible crash on API 21+ at launch when using Holo theme and FormsApplicationAct...

* Fix possible crash on API 21+ at launch

* Do not use an explicit cast

* Do not use C# 7 pattern matching

diff --git a/Xamarin.Forms.Platform.Android/Platform.cs b/Xamarin.Forms.Platform.Android/Platform.cs
index add84eb..fe588eb 100644 (file)
--- a/Xamarin.Forms.Platform.Android/Platform.cs
+++ b/Xamarin.Forms.Platform.Android/Platform.cs
@@ -847,24 +847,28 @@ namespace Xamarin.Forms.Platform.Android
                        Color navigationBarTextColor = CurrentNavigationPage == null ? Color.Default : CurrentNavigationPage.BarTextColor;
                        TextView actionBarTitleTextView = null;
 
-                       if(Forms.IsLollipopOrNewer)
+                       if (Forms.IsLollipopOrNewer)
                        {
                                int actionbarId = _context.Resources.GetIdentifier("action_bar", "id", "android");
-                               if(actionbarId > 0)
+                               if (actionbarId > 0)
                                {
-                                       Toolbar toolbar = (Toolbar)((Activity)_context).FindViewById(actionbarId);
-                                       
-                                       for( int i = 0; i < toolbar.ChildCount; i++ )
+                                       var toolbar = ((Activity)_context).FindViewById(actionbarId) as ViewGroup;
+                                       if (toolbar != null)
                                        {
-                                               if( toolbar.GetChildAt(i) is TextView )
+                                               for (int i = 0; i < toolbar.ChildCount; i++)
                                                {
-                                                       actionBarTitleTextView = (TextView)toolbar.GetChildAt(i);
-                                                       break;
+                                                       var textView = toolbar.GetChildAt(i) as TextView;
+                                                       if (textView != null)
+                                                       {
+                                                               actionBarTitleTextView = textView;
+                                                               break;
+                                                       }
                                                }
                                        }
                                }
-                       }
-                       else
+                       }                       
+
+                       if (actionBarTitleTextView == null)
                        {
                                int actionBarTitleId = _context.Resources.GetIdentifier("action_bar_title", "id", "android");
                                if (actionBarTitleId > 0)