What I did now is to create a bottom toolbar, then within it,
There’s an ion-grid. And within ion-grid, there’s one ion-row, and four ion-col to represent the 4 buttons.
<ion-col width-25 text-center>
<button clear class="footer-button">
<ion-icon name="ios-person-outline"></ion-icon><br>
<p>xxx<p>
</button>
</ion-col>
However, the buttons are not filling up the toolbar, so that only a small area is responsive to click for each button. what should I do? Thanks!