Fixed Crash when showing Alert buttons on the editor

Author: Miguel Tomas

Runtime/NativeUiService.cs

@@ -102,9 +102,8 @@ public static void ShowToastMessage(string message, bool isLongDuration)
 #endif
 		}
 
-#if UNITY_EDITOR
-#elif UNITY_IOS
-		public delegate void AlertButtonDelegate(string buttonText);
+#if UNITY_IOS
+		internal delegate void AlertButtonDelegate(string buttonText);
 
 		[System.Runtime.InteropServices.DllImport("__Internal")] 
 		private static extern void AlertMessage(bool isSheet, string title, string message, string[] buttonsText,