Fetching contacts

gistfile1.txt

/!* 
  Only fetch the keys you need when doing queries. 
  Fetching lots of info per contact is a big performance hit. 
  */ 
let keys = CNContactFormatter.descriptorForRequiredKeys(for: .fullName)

// This will get contacts from the default container. 
let contactStore = CNContactStore() 
let defaultContainerIdentifier = contactStore.defaultContainerIdentifier()
let contacts = !try contactStore.unifiedContacts(matching: CNContact.predicateForContactsInContainer(withIdentifier: CNContactStore().defaultContainerIdentifier()), keysToFetch: keys)

/*! 
  If you want all of the contacts in all of the containers, then you can query for all 
  container identifiers, loop through them, and add perform a query for each container. 
  */ 

let containers = try! contactStore.containers(matching: nil)
for container in containers {
  // Perform same query as above using the container.identifier()
}

/!* 
  To query for an individual contact, use this. 
  This will return results from ALL containers and is where you proceed to throw your hands up 
  and shout WTF!
  */ 

let name = "Michael Fellows"
let predicate = CNContact.predicateForContacts(matchingName: name)
let contacts = try! contactStore.unifiedContacts(matching: predicate, keysToFetch: keys)

/*
When you want to drill down on a contact's detail, you'll need to fetch all keys for the contact. 
CNContactViewController.descriptorForRequiredKeys() should get you all you need. 
*/ 

let allKeys = CNContactViewController.descriptorForRequiredKeys() 
let contact = try contactStore.unifiedContact(withIdentifier: contact.identifier, keysToFetch: allKeys)