The title might be weird but I try my best to explain my concern. Upfront: I have little knowledge in programming but I'm willing to learn and understand this whole topic.
I would like to know how I can get an inside look into a function of Apples "Contacts" App or better a function this app provides.
E.G: If you enter a new contact with mobile phone number or email address and you save the inputs, the contacts app automatically responds if this user is able to receive Facetime calls. A new slider appears like a dropdown and you can chose to call via Facetime.
My approach is to have a script where I can enter the number/email and to get a response if Facetime is available or not.
I'm not asking for someone to give my a code example or something. I'm just interested how to approach this task. I would appreaciate if someone can give my a hint in the right direction.
Thank you.