$appUrl = "https://itunes.apple.com/us/rss/topfreeapplications/limit=400/genre=6014/json";

$appStore = new APPSTORE();
$json_appdata = $appStore->downloadApps($appUrl);

$appdata_array = json_decode($json_appdata, true);
//print_r($appdata_array);

foreach ($appdata_array["entry"] as $row) {
    print_r($row["im:name"]);
}

Notice: Undefined index: entry on line 13 which is in foreach.

Warning: Invalid argument supplied for foreach() on line 13

foreach ($appdata_array['feed']['entry'] as $row) {
    print_r($row["im:name"]);
}

array (size=1)
  'feed' =>
    array (size=8)
      'author' =>
        array (size=2)
          'name' =>
            array (size=1)
              'label' => string 'iTunes Store' (length=12)
          'uri' =>
            array (size=1)
              'label' => string 'http://www.apple.com/itunes/' (length=28)
      'entry' =>
        array (size=400)
          0 =>
            array (size=12)
              'im:name' =>
                array (size=1)
                  'label' => string '2048' (length=4)
              'im:image' =>
                array (size=3)