Can I use iCloud as Back End server for and iOS App?

I am creating an iPhone App. I have some tables to save users information. Do, I need to have a back end web server to store database or I can use iCloud storage without need to web server? CoreData can be used to save data in iOS devices but there need to be some remote db too, isn't it? Can that remote db be iCloud Storage.

Any tips and information is highly appreciated.

Regards

use iCloud as a web server is impossible.

Short answer: Whose iCloud account are you going to use? Yourself? User's? Apples never gives any API for an IN-App iCloud Account login, and it can only be set in Device's Setting.