<view class="dm-switch {{className}}" onTap="onDmTap">
  <view>
    <view class="{{_checked ? 'dm-switch-bg-check' : 'dm-switch-bg-uncheck'}}"></view>
    <view class="{{_checked ? 'dm-switch-radio-check' : 'dm-switch-radio-uncheck'}}"></view>
  </view>
  <!--在switch组件上覆盖一层透明度的做法是为了适配weex，weex下如果是position:absolute,在父层节点设置opacity不生效-->
  <view a:if="{{disabled}}" class="dm-switch-disabled"></view>
</view>