NativeScript/apps/ui/app/tab-view/icon-title-placement-page.xml

<Page>
  <TabView style="color: green;">
    <TabView.items>
      <TabViewItem title="Title" automationText="tab1"  iconSource="res://add_to_fav">
        <TabViewItem.view>
          <GridLayout>
            <Label text="Title and icon" verticalAlignment="center" horizontalAlignment="center"/>
          </GridLayout>
        </TabViewItem.view>
      </TabViewItem>
      <TabViewItem iconSource="res://add_to_fav" automationText="tab2" >
        <TabViewItem.view>
          <GridLayout>
            <Label text="Only icon" verticalAlignment="center" horizontalAlignment="center"/>
          </GridLayout>
        </TabViewItem.view>
      </TabViewItem>
      <TabViewItem title="Title" automationText="tab3">
        <TabViewItem.view>
          <GridLayout>
            <Label text="Only title" verticalAlignment="center" horizontalAlignment="center"/>
          </GridLayout>
        </TabViewItem.view>
      </TabViewItem>
    </TabView.items>
  </TabView>
</Page>