Let me introduce myself - my name is Denis Mukha and I've been developing applications for the iOS platform since the appearance of iOS 4 and starting with MRC. In 2015 I started using CoreData and now in our project, we have 6 different databases with millions of objects and more than a hundred tables. So I decided to write a little blog about CoreData to share my knowledge of this framework and describe all the issues that I faced during these years. I hope this will help other people to find answers to some tricky questions about CoreData as Apple documentation is not perfect, to be honest. I will mostly focus on the SQLite type of persistent stores in this blog but will mention some other types as well. Also, I will try to go from the basics of this framework mentioning of course that CoreData is not an ORM and then will dive into some specific details trying to show how powerful it is when you know how to use it properly. I will describe some issues in the framework and what is better not to use and why, and what everyone should know right from the beginning to build a better architecture for large CoreData projects.