ionic col不能换行解决办法

<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,因为布局是用的flex,查看布局后的css:flex-wrap:wrap;