title: How to order results when using typeahead from ngx-bootstrap?
body: <p>I am using customTemplate for my typeahead which has three fields </p>
  
  <p><code>({{model.number}}-{{model.city}}-{{model.state}})</code></p>
  
  <p>using the <code>number</code> as the <code>typeaheadOptionField</code>, I see there is <code>typeaheadGroupField</code> available which I use on the number field .... I would like to know is there anyway in which I can <code>order</code> the result based on the <code>city</code> field?</p>
  
  <pre><code>&lt;ng-template #customCapTemplate let-model="item" let-index="index"&gt;
     &lt;h5&gt;{{model.code}}-{{model.city}}-{{model.prov}}&lt;/h5&gt;
  &lt;/ng-template&gt;
  &lt;input name="colCap" [typeahead]="capList" typeaheadGroupField="code" 
      typeaheadOptionField="code" [typeaheadItemTemplate]="customCapTemplate" class="form-control"&gt;
  </code></pre>
  
  <p>currently it is showing the result like this 
  <a href="https://i.stack.imgur.com/RNQeM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RNQeM.png" alt="enter image description here"></a></p>