(Ionic 2) Grouping label inside select box
<p>I need to create the multiple checkbox  select box that have grouping label inside the box.
Example</p>

<p>-Appetizer:</p>

<p>---Salad</p>

<p>---etc</p>

<p>-Main Course:</p>

<p>---Steak</p>

<p>---etc</p>

<p>-Desert:</p>

<p>---Ice Cream</p>

<p>---etc</p>

<p>This is my code:</p>

<blockquote>
<pre><code>&lt;ion-select [(ngModel)]="food" multiple="true"&gt;
                        &lt;ion-label&gt;Toppings&lt;/ion-label&gt; &lt;!-- I want to create group label in here --&gt;
                        &lt;ion-option&gt;Bacon&lt;/ion-option&gt;
                        &lt;ion-option&gt;Black Olives&lt;/ion-option&gt;
                        &lt;ion-option&gt;Extra Cheese&lt;/ion-option&gt;
                        &lt;ion-option&gt;Mushrooms&lt;/ion-option&gt;
                        &lt;ion-option&gt;Pepperoni&lt;/ion-option&gt;
                        &lt;ion-option&gt;Sausage&lt;/ion-option&gt;
 &lt;/ion-select&gt;
</code></pre>
</blockquote>

<p>How to create the grouping label inside the ion-select? Thanks..</p>