objective c - Create a CardDav client to fetch contacts from server in iOS -

i have read questions here on regarding carddav , didn't find answer question. let me know if answered.

i need create app implements carddav client fetch contacts server. aware of using existing addressbook framework , make ios heavy lifting. however, our app more catered elderly people , business feels not might able navigate settings , add server information manually. (i looking automating this, information thread).

1. is there sdk available in objective c can use fetch/edit , delete contacts.
2. is there way avoid syncing of existing contacts other sources icloud or gmail synced our server when default account switched.

any pointers or guide build native carddav client appreciated.

many thanks