title: iOS FCM data only message does not call messaging:didReceiveMessage
body: <p>Firebase Messaging version <code>5.6.0</code>. I am attempting to <a href="https://firebase.google.com/docs/cloud-messaging/ios/receive#handle-data-messages-in-foregrounded-apps" rel="nofollow noreferrer">handle a data only message in the foreground</a> via Firebase Messaging on iOS 9.0 (10 if needed), but it is not calling <code>FIRMessagingDelegate</code>'s <code>messaging:didReceiveMessage</code> per the documentation. I see the message come in @ <code>FIRMessaging.m</code>'s <code>appDidReceiveMessage:message</code>, but never comes through to the delegate.  </p>
  
  <p>This is the snippet from the cloud function that sends data to the topic per <a href="https://firebase.google.com/docs/cloud-messaging/admin/send-messages#send_to_a_topic" rel="nofollow noreferrer">sending to a topic</a>:</p>
  
  <pre><code>const message = {
    data: {
      test: '123'
    }
    topic: 'example'
  }
  admin.messaging().send(message);
  </code></pre>
  
  <p>Did I miss something?</p>
  
  <p>Update: I do receive the data if I implement application:didReceiveRemoteNotification:userInfo
  fetchCompletionHandler:completionHandler.</p>