Programming iOS 12

Chapter 18. Contacts

The user’s contacts constitute a contacts database. The user can interact with this database through the Contacts app. Your code can access it programmatically through the Contacts framework. You’ll need to import Contacts. An interface, similar to the Contacts app, for letting the user interact with the contacts database from within your app is provided by the Contacts UI framework. You’ll need to import ContactsUI.

Access to the contacts database requires user authorization. You’ll use the CNContactStore class for this. To learn what the current authorization status is, call the class method authorizationStatus(for:) with a CNEntityType of .contacts. (This a curious requirement, as .contacts is the only CNEntityType!) To ask the system to put up the authorization request alert if the status is .notDetermined, call the instance method requestAccess(for:completionHandler:). The Info.plist must contain some text that the system authorization request alert can use to explain why your app wants access. The relevant key is “Privacy — Contacts Usage Description” (NSContactsUsageDescription). See “Checking for Authorization” for a discussion of authorization strategy.

Contact Classes

Here are the chief object types you’ll be concerned with when you work with the user’s contacts:

CNContactStore

The contacts database is accessed through an instance of the CNContactStore class. You do not need to keep a reference to an instance of this class. When you want to fetch ...