我想设置picker-view选中第二个item，item从0开始，不过我设置了picker-view的value为[2]之后，发现还是没有选中，相关代码如下：

------------------------------------------------------------------------------wxml

<picker-view indicator-style="height: 50px;" style="width: 100%; height: 420rpx;" bindchange="bindChangePlan" indicator-style="{{style}}" value="{{selectedPlanIndex}}">

       <!--完成天数  -->

       <picker-view-column>

         <view wx:for="{{planList}}" style="line-height: 50px">{{item.levelName}}</view>

       </picker-view-column>

     </picker-view>

---------------------------------------------------------------------------------js

var selectedPlanIndex = [2];

Page({

 /**

  * 页面的初始数据

  */

 data: {

   style:'background-color:#BCD7FF;height:50px;opacity:0.6',

   scrollLeft: scrollLeft,

   numPerDay: numPerDay,

   planList: [],

   planConfig:null,

   day:day,

   selectedNum: selectedNum,

   selectedDay: selectedDay,

   selectedPlanIndex: selectedPlanIndex

 },

另外我发现planList如果是纯数字数组，比如[2001,2002,2003],对value设置selectedPlanIndex=[2]，就可以选中2003这个item。而我的planList里面存放的是一个自定义数组，是不是跟这个有关系呢。

planList的自定义数组内容如下：

[{"levelName":"CET4","levelCodeValue":"1","wordCount":3873},{"levelName":"CET6","levelCodeValue":"2","wordCount":5488},{"levelName":"初高中","levelCodeValue":"3","wordCount":2520},{"levelName":"雅思红宝书","levelCodeValue":"4","wordCount":3593},{"levelName":"雅思807听力","levelCodeValue":"5","wordCount":0},{"levelName":"GRE","levelCodeValue":"6","wordCount":7527},{"levelName":"GMAT","levelCodeValue":"7","wordCount":2432},{"levelName":"TEM4","levelCodeValue":"8","wordCount":0},{"levelName":"TEM8","levelCodeValue":"9","wordCount":4111},{"levelName":"高中词汇","levelCodeValue":"10","wordCount":386},{"levelName":"TOEFL","levelCodeValue":"11","wordCount":3906},{"levelName":"IELTS","levelCodeValue":"12","wordCount":3956}]