页面可左右滑动 下滑刷新 ；后端请求数据正常bbsList：140条

但是wxml仅能显示50条数据 再次下滑无页面未填充 setdata正常真机调试如下

  此为wxml代码

<swiper current="{{currentTab}}" bindchange="swiperChange" duration='300' class="tab-content">

    <swiper-item wx:for="{{categoryLists.length}}" wx:key="this">

      <scroll-view scroll-y="true" bindscrolltolower="toLowFun" class="scoll-h">

        <view wx:for="{{bbsList}}" wx:for-item="bbs" wx:key="bbs">

          <view class="item-ans">

            <view class="expertInfo">

              <view class="review-item-head">

                <view class="review-item-head-lf lm26 color-333">

                  <image class="review-avatar" bindtap="linkToIndDefenderOfFranceexDetailInfo" data-id="{{bbs.userManage.identity == 2 || bbs.userManage.identity == 1 ? '':bbs.userManage.id}}" src="{{bbs.userManage.headPic==''?avatarDefault:bbs.userManage.headPic}}" mode="aspectFill"></image>

                </view>

                <view class="review-avatar-right" bindtap="linkToBbsDetail" data-id="{{bbs.id}}">

                  <view class="title">

                    {{bbs.userManage.loginCode}}

                    <block wx:if="{{bbs.userManage.identity == 1}}" space="ensp">

                      <text class="color-999" style="margin-left:15rpx;">会员</text>

                    </block>

                    <block wx:if="{{bbs.userManage.identity == 2 && bbs.userManage.bodyguardType == ''}}" space="ensp">

                      <text class="color-999" style="margin-left:15rpx;">教师</text>

                    </block>

                    <block wx:else space="ensp">

                      <text class="color-999" style="margin-left:15rpx;">{{bbs.thingsClassify.classifyIdentity}}</text>

                    </block>

                    <text class="color-999" style="margin-left:220rpx;">{{bbs.time}}</text>

                  </view>

                  <view class="control">

                    <block wx:if="{{bbs.readNum > 0 }}" space="ensp">

                      <image style="width:38rpx;height:38rpx; " src="../../images/yanjing.png" mode="aspectFill" />

                      <text class="color-999" style="margin-left:5rpx;">{{bbs.readNum}}</text>

                    </block>

                  </view>

                </view>

              </view>

              <view class="center">

                <view class="article">

                  <view class="pay-hint-content {{bbs.showMore?'ellipsis':'unellipsis'}}">

                    {{bbs.explain}}

                  </view>

                  <view style="color: #1da39a;" wx:if='{{bbs.explain.length > 100}}' bindtap="linkToShowMoreExplain" data-id='{{bbs.id}}' data-showMore='{{bbs.showMore}}'>

                    {{bbs.showMore ? '显示更多':'收起'}}

                  </view>

                </view>

              <view class="bottom">

                <view class="btn-left" bindtap="linkToBbsDetail" data-id="{{bbs.id}}">

                  <image class="" style="width:30rpx;height:28rpx;margin-top:15rpx;" src="{{baseImgUrl}}yingshixiangq_fenxiang.png" mode="aspectFill" />

                  <block wx:if="{{bbs.forwardNum != 0}}" space="ensp">

                    {{bbs.forwardNum}}

                  </block>

                  <block wx:else space="ensp">

                    转发

                  </block>

                </view>

                <view class="btn-left" bindtap="linkToBbsDetail" data-id="{{bbs.id}}">

                  评论

                  <block wx:if="{{bbs.replyNum != 0}}" space="ensp">

                    {{bbs.replyNum}}

                  </block>

                </view>

                <view class="btn-left" bindtap="zan" data-bbsid='{{bbs.id}}' data-tapStatus='{{bbs.tapStatus}}'>

                  <block wx:if="{{bbs.praiseNum != 0}}" space="ensp">

                    <image class="" style="width:32rpx;height:28rpx;margin-top:15rpx;" src="{{bbs.tapStatus==1?isZan:noZan}}" mode="aspectFill" /> {{bbs.praiseNum}}

                  </block>

                  <block wx:else space="ensp">

                    <image class="" style="width:32rpx;height:28rpx;margin-top:15rpx;margin-right:5rpx;" src="{{bbs.tapStatus==1?isZan:noZan}}" mode="aspectFill" />赞

                  </block>

                </view>

              </view>

            </view>

          </view>

        </view>

      </scroll-view>

    </swiper-item>

  </swiper>

不知该如何优化。。。