ionic col不能換行解決辦法

<div class="row row-wrap">
<div class="col col-50">1</div>
<div class="col col-50">1</div>
<div class="col col-50">1</div>
<div class="col col-50">1</div>
</div>

注：需要增加class=row-wrap,因爲佈局是用的flex,查看佈局後的css:flex-wrap:wrap;