见代码片段，运行时，检查console里的日志

<swiper bindchange="onChange" style="background-color: red;">
  <swiper-item>
    <level1 wx:if="{{show[0]}}">
      <view>直接初始化，会执行pageLifetimes.show</view>
    </level1>
  </swiper-item>
  <swiper-item>
    <level1 wx:if="{{show[1]}}">
      <view>不初始化，不会执行pageLifetimes.show</view>
    </level1>
  </swiper-item>
</swiper>