Loading Spinner - Shopify polaris

[Ido1425]

Hi everyone!

I am developing an app.

I want to display the loading spinner when the action of the app is in progress (the user submit form in the app that make changes in the product pages). 

I have built a component of form in different file that activate the backend action. 

I only succeeded to display the spinner above the submit form when the action is in progress.

how do display it the middle of the page instead of the content in the loading time