Hi Mostafa,
Don't know exactly which version of Mobile do you have but in v9 you can manage to do that by these changes:
- Find page
id="createSR" and in the section state name="isRequired" change boolean value from false to true for state name="location".
<page id="createSR" title="New request" hidden="{!page.state.canLoad.page}" controller="CreateSRController">
<states id="a8pz5">
(...)
<state name="isRequired" type="object" id="jwje3">
(...)
<state name="location" type="boolean" value="true" id="wv5g6"/>
(...)
</state>
</states>
</page>
- Mark "Location" field as required (blue dot will be visible close to the field). To do that please add required tag
required="{page.state.isRequired.location}" for label:
<page id="createSR" title="New request" hidden="{!page.state.canLoad.page}" controller="CreateSRController">
(...)
<label label="Location" tooltip-text="Identifies the location for the ticket." required="{page.state.isRequired.location}" id="ya5q6"/>
(...)
</page>