Dynamic binding for sap.m.switch in a sap.m.Table

I have a requirement where we need to show data in sap.m.Table where columns are Question and Ans.

For objective type question the Ans column should have a sap.m.switch instead of a free text.

I am able to do up to this.

However I am having issue in binding the state of the sap.m.switch control.

My table definition is:

<Table id="idQATable1"

inset="false"

items="{

path: '/QA',

sorter: {

path: 'QuestionType'}

/>

  <headerToolbar>...</headerToolbar>

  <columns>

  <Column1.../>

  <Column2.../>

  </Columns>

  <items>

      <ColumnListItem >

  <cells>

  <Text text="{Question}" />

  <Switch state="{Ans==true}" customTextOn="Yes" customTextOff="No"/>

  </cells>

      </ColumnListItem>

  </items>

</Table>

The issue is the data type on the table for "Ans" is String but Switch state is a boolean value. I tried with putting condition check directly in the binding

state="{Ans==true}". But this is always returning false. so the switch is showing in false state always.

Please help on how to put such conditions within table column?

Thanks

Shibaji