title: msbuild array iteration
body: <pre><code>&lt;ItemGroup&gt;
      &lt;!-- Unit Test Projects--&gt;
      &lt;MyGroup Include="Hello.xml" /&gt;
      &lt;MyGroup Include="GoodBye.xml" /&gt;     
  &lt;/ItemGroup&gt;
  </code></pre>
  
  <p>How do I make a task that iterates through this list and does something?</p>
  
  <pre><code>&lt;XmlPeek XmlInputPath="%(MyGroup.Identity)"
           Query="/results"&gt;
      &lt;Output TaskParameter="Result"
              ItemName="myResult" /&gt;
  &lt;/XmlPeek&gt;
  </code></pre>
  
  <p>I want to thow an error message if myresult has a certain text inside of it.  However for the life of me I can't figure out how to iterate through arrays in Msbuild... anyone know how to accomplish this?</p>