为什么<swiper>外层加一个<view class="container">轮播不显示？

<!--index.wxml-->

<view class="container">

<swiper indicator-dots="{{indicatorDots}}"

autoplay="{{autoplay}}" interval="{{interval}}" duration="{{duration}}">

<block wx:for="{{imgUrls}}" wx:key="property">

<swiper-item>

<image src="{{item}}" class="slide-image" width="355" height="150"/>

</swiper-item>

</block>

</swiper>

</view>