使用simplexmlPHP读取xmlattribut导致双foreach循环失败

我是通过PHP simplexml_load_file读取XML的初学者。我的问题是读出具有ID作为属性的单个元素。此外，我想用黑色回显所有类型（用HEX代码搜索：#000000，因为它在变体中甚至不是相同的id）。

请参阅下面的示例：

文件.xml

<products>
        <types>
           <name>Artikel</name>
           <description>blablabla</description>
           <variations>
             <variation id=2>
               <name>black</name>
               <colors>
                 <color index="1">#000000</color>
               </colors>
            </variation>
          <variations>
            <variation id=1>
              <name>white</name>
              <colors>
               <color index="2">#FFFFFF</color>
              </colors>
          </variation>
         </variations>
       </types>
       <types>
           <name>Artikel</name>
           <description>blablabla</description>
           <variations>
             <variation id=7>
               <name>black</name>
               <colors>
                 <color index="6">#000000</color>
               </colors>
            </variation>
          <variations>
            <variation id=90>
              <name>black</name>
              <colors>
               <color index="3">#000000</color>
              </colors>
          </variation>
         </variations>
       </types>
    </products>

使用PHP，我可以找到所有的：

<?php
    $products = simplexml_load_file(xml.file);
        /*echo '<pre>';
        print_r ($products); //all products
        echo '</pre>';*/
        foreach ($products as $types)
        {
            echo '<pre>';
            print_r ($types);
            echo '</pre>';
            foreach ($products->variation as $variation)
            {
                echo '<pre>';
                echo $variation;
                echo '</pre>';
            }
                        if (color == #00000)  /*I know this is wrong, it is just my base for solving*/
                        {
                                echo types;
                        }
        }
?>

代码PHP项目：

  <?php
    $productTypes = simplexml_load_file('http://api.spreadshirt.net/api/v1/shops/611779/productTypes?fullData=true');
        /*echo '<pre>';
        print_r ($productTypes);
        echo '</pre>';*/
        foreach ($productTypes as $productType)
        {
            /*echo '<pre>';
            print_r ($productType);
            echo '</pre>';*/
            foreach ($productType->appearances->appearance[0] as $appearances)
            {
                //echo $appearances. '</br>';
                foreach ($appearances->colors->color['#000000'] as $color)
                {
                    echo $color. '</br>';
                    if ($color == 'black');
                    {
                    echo $color;
                    }
                }
            }
        }
?>