title: resultCallback for Unity Ads to only reward if video finished
body: <p>I recently added unity ads to a working game I had, and i want to figure out how to use the rewarded videos ad placements to make sure I only give the reward when the video is not skipped.
  I already have unity ads working, and here is my code:</p>
  
  <pre><code>private static bool PlayUnityVideoAd()
  {
      string adString = PlayerPrefs.GetString ("UnityAds"+adName);
      if (Advertisement.isReady (adString)) {
          Advertisement.Show (adString, new ShowOptions {
              pause = true,
              resultCallback = result =&gt; {
                  Debug.Log (result.ToString ())
              }
          });
          return true;
      }
      return false;
  }
  </code></pre>
  
  <p>What do I need to change to have the function only return true if <code>ShowOptions.resultCallback</code> is set to Finished?
  I tried to replace the <code>Debug.Log</code> line with a line to return a value from a switch, but it crashed unity.
  I also have a feeling that <code>Advertisement.isShowing</code> might be needed to make sure to wait for the end of the video, but I don't know how to implement it.
  So, the results I want are:<br>
  Finished => <code>return true;</code><br>
  Failed => <code>return false;</code><br>
  Skipped => <code>return false;</code>  </p>
  
  <p>Notes:<br>
  I am using <code>PlayerPrefs</code> to store the IDs for the different ad placement (<code>adString</code>).<br>
  This is part of a cascade with multiple ad networks, which is why i want it to return true or false.</p>