title: Firebase Analytics ITEM_ID vs CONTENT_TYPE
body: <p>In my iOS app, I'm using the following Firebase Analytics function call:</p>
  
  <pre><code>Analytics.logEvent(AnalyticsEventSelectContent, parameters: [
      AnalyticsParameterItemID: "id-button",
      AnalyticsParameterContentType: "button"]
  )
  </code></pre>
  
  <p>I know I can put any <code>String</code> for the ItemID and ContentType parameters, but what's the intended use for each of these parameters? How are they supposed to be different?</p>