position element at center of absolute layout in nativescript

Place a GridLayout inside the AbsoluteLayout, then place the Button which should be centered inside the GridLayout:

<AbsoluteLayout  class="list-item">
    <Image src="{{item.photo}}" *ngIf="item.photo" stretch="fill">  </Image>
    <GridLayout background="transparent">
        <Button [text]="item.name" (tap)="onItemTap(item)"></Button>
    </GridLayout>
</AbsoluteLayout>