ui:input select on change event in lightning

I have one scenario in which wrapper list is iterating using aura iteration. Inside iteration there is one text field and one dropdown ui:inputselect and ui:inputSelectOption options are also coming dynamically which contains fields.
I want if one value in dropdown is changed, the text field gets changed.

For ex. If I select any date field from dropdown, the text field should be converted and one date picker should appear.

How to get which field is changed because we cannot have dynamic aura:id.

<aura:iteration items="{!v.wrapperList}" var="wrap" indexVar="i">
    <tr>
        <td>C:{!i+1}</td>                           

        <td>
            <ui:inputSelect multiple="false" value="{!wrap.fieldName}" class="form-control">
                <ui:inputSelectOption text="Select Field" label="Select Field" disabled="true" class="form-control"/>
                <aura:iteration items="{!v.objFieldsList}" var="fields">
                    <ui:inputSelectOption text="{!fields}" label="{!fields}" class="form-control"/>
                </aura:iteration>
            </ui:inputSelect>
        </td>

        <td>
            <ui:inputSelect multiple="false" value="{!wrap.opVal}" class="form-control">
                <ui:inputSelectOption value="=" text="EQUALS" label="EQUALS" class="form-control"/>
                <ui:inputSelectOption value="!=" text="NOT EQUALS" label="NOT EQUALS" class="form-control"/>
            </ui:inputSelect>
        </td>

        <td>
            <ui:inputText placeholder="Value" value="{!wrap.fieldVal}" class="form-control" required="true"/>
        </td>

    </tr>
</aura:iteration>