restore compatibility with iOS and Android

mobile.netbiblio.php

@@ -305,6 +305,12 @@ class NetBiblio extends WebService
             throw new WebException("CallArg", "Argument must be valid JSON.", -42);
         }
 
+        // The iOS and Android applications still uses 'category' instead of 'genre'
+        if(isset($queryArray['category']) && is_array($queryArray['category'])) {
+            $queryArray['genre'] = $queryArray['category'];
+            unset($queryArray['category']);
+        }
+
         $bs = new BookSearch();
 
         if (isset($queryArray['queryType'])) {
@@ -370,6 +376,12 @@ class NetBiblio extends WebService
         return AudioBook::ListOfGenres();
     }
 
+    public function ListOfCategories()
+    {
+        // this method exists for compatibility purpose with the Android and iOS applications
+        return $this->ListOfGenres();
+    }
+
     public function ListOfTypes()
     {
         return array_filter(AudioBook::listOfTypes(), function ($t) {