Data sync from SQL DB to the application local storage

Hi All, I am very new to Xamarin and We are developing a cross platform app (iOS, Android) for contact management (Listing, add, edit) and WCF service for connecting the applications with the SQL DB. We are using SQLite DB for local storage. Our requirement is to enable Datasync functionality from the server to the Local storage of the users mobile in every 24 hours. everyday night at 12 AM, data sync operation should be triggered and pass the data from the service [from my SQL DB] and store it in the SQLite DB of all the users devices. So when the user uses his app in the mobile, it will fetch the data from SQLite DB.

Please advise what is the best way of achieve this functionality. If possible please share the sample code

Thanks Jeevitha