title: How to upload contacts as Iterable from Flutter to Firestore
body: <p>I'm creating an app which will upload all contacts to Firestore database with map type. But below code do not upload contacts to Firestore. Please help.</p>
  
  <p>I have been trying to fetch contacts from my phone to Firestore using Flutter app. I used contact_services library to fetch contacts. Even after trying some similar examples, I could not my contacts to Firestore using map type. Where do I make changes so that I can upload all my contacts as map value to Firestore</p>
  
  <pre><code>final Iterable&lt;Contact&gt; contacts = await ContactsService.getContacts(withThumbnails: false);
  Firestore.instance
              .collection('contacts')
              .document(firebaseUser.uid)
              .setData({
            'contact':{ contacts.map((Contact contact){ 'name': contacts.displayName,contacts.phone})}  
          });
  </code></pre>
  
  <p>I expected to display all my contacts in firestore with map type, but actual output is none were uploaded.</p>