ionic二级导航栏/Sub Header
A secondary header bar can be placed below the original header bar. There are quite a few more ways to customize Headers. Have a look at Button Bars to get other ideas on how it could be used.
<divclass="bar bar-header"><h1class="title">Header</h1></div><divclass="bar bar-subheader"><h2class="title">Sub Header</h2></div>
Also, remember to include the has-subheader
CSS class to your ion-content
directive.