Conditional Rendering in Lightning Component

<aura:component >
    <aura:attribute name="edit" type="Boolean" default="true"/>
    <aura:if isTrue="{!v.edit}">
        <lightning:buttonGroup>
            <lightning:button label="Refresh" />
        <lightning:button label="Edit"/>
        <lightning:button label="Save"/>
    </lightning:buttonGroup>
        <aura:set attribute="else">
            <ui:button label="Edit" />
        </aura:set>
    </aura:if>
</aura:component>