SQLLite in IOS to merge with main DB

I am designing an IOS app which generates quotations for customers. The app would have a db server (SQL Server) as its backend and would be written in Xcode.

The app would need to generate a quotation even when there is no connection to the backend database. I would be using SQLLite for that purpose. My question is about connection to the main SQL Server Database.

1. Is it possible to connect to SQL Server in a IOS device? Do I need any to buy any third party software or it’s a built in support? (Sorry I am new to this)
2. How would the SQLite merge with the main database when the connection comes back up? It is at all possible? Any better ideas?