How would i retrieve all containers or all container identifiers from a contact store?
The instance method containers(_:) of the CNContactStore class requires a predicate from one of the class methods of the CNContainer class that returns a predicate.
Here are all the class methods of CNContainer that return a predicate:
class func predicateForContainerOfContact(withIdentifier: String) -> NSPredicate
Returns a predicate to find the container of the specified contact.