How to secure my application contacts like Facebook

Question

When you try to retrieve contacts from device , you generally get contacts created by all applications except Facebook. This question describes it.

So , what would I need to do when I'm storing contacts through my applications(using ContactsContract?), so that other applications won't be able to retrive it through ContactsContract ..but they are still available to device contacts application... or to the applications that I choose ?

Answer 1

Facebook contacts are synced using a different implementation of the Contacts API. Google used to provide a special case for this, but no longer does. The different hardware manufacturers that do support it customize their Contacts application for this specific use. This is why Facebook contact sync works on most phones besides the Nexus series. These are private implementations, but I'm sure can be reverse engineered if you're willing to sort through lots of obfuscated code.