In an app we are going to have a section called Directory.
We shall access the Phone directory and obtain all the contact names and their numbers.
Each time the app is opened, this list is to synchronise. Each time this happens, we are going to do an ajax call to the server where we send the database each of the contacts' phone number.
If the phone number exists, we send back a positive response. This will generate a list from our mobile phone book of contacts that have signed up to the app service.
(Works similar to Whatsapp - only show contacts from phone book who are subscribed to ACN)
To work on iOS and Android.