SKILL.md
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Setup
Project Configuration
- Add
NSContactsUsageDescriptionto Info.plist explaining why the app accesses contacts
- No additional capability or entitlement is required for basic Contacts access
- For contact notes access, add the
com.apple.developer.contacts.notesentitlement
Imports
import Contacts // CNContactStore, CNSaveRequest, CNContact
import ContactsUI // CNContactPickerViewController
Authorization
Request access before fetching or saving contacts. The picker (CNContactPickerViewController)
does not require authorization -- the system grants access only to the contacts
the user selects.
let store = CNContactStore()
func requestAccess() async throws -> Bool {
return try await store.requestAccess(for: .contacts)
}
// Check current status without prompting
func checkStatus() -> CNAuthorizationStatus {
CNContactStore.authorizationStatus(for: .contacts)
}
Authorization States
Status
Meaning
.notDetermined
User has not been prompted yet
.authorized
Full read/write access granted
.denied
User denied access; direct to Settings
.restricted
Parental controls or MDM restrict access
.limited
iOS 18+: user granted access to selected contacts only
Fetching Contacts
Use unifiedContacts(matching:keysToFetch:) for predicate-based queries.
Use enumerateContacts(with:usingBlock:) for batch enumeration of all contacts.
Fetch by Name
func fetchContacts(named name: String) throws -> [CNContact] {
let predicate = CNContact.predicateForContacts(matchingName: name)
let keys: [CNKeyDescriptor] = [
CNContactGivenNameKey as CNKeyDescriptor,
CNContactFamilyNameKey as CNKeyDescriptor,
CNContactPhoneNumbersKey as CNKeyDescriptor
]
return try store.unifiedContacts(matching: predicate, keysToFetch: keys)
}
Fetch by Identifier
func fetchContact(identifier: String) throws -> CNContact {
let keys: [CNKeyDescriptor] = [
CNContactGivenNameKey as CNKeyDescriptor,
CNContactFamilyNameKey as CNKeyDescriptor,
CNContactEmailAddressesKey as CNKeyDescriptor
]
return try store.unifiedContact(withIdentifier: identifier, keysToFetch: keys)
}
Enumerate All Contacts
Perform I/O-heavy enumeration off the main thread.
func fetchAllContacts() throws -> [CNContact] {
let keys: [CNKeyDescriptor] = [
CNContactGivenNameKey as CNKeyDescriptor,
CNContactFamilyNameKey as CNKeyDescriptor
]
let request = CNContactFetchRequest(keysToFetch: keys)
request.sortOrder = .givenName
var contacts: [CNContact] = []
try store.enumerateContacts(with: request) { contact, _ in
contacts.append(contact)
}
return contacts
}
Key Descriptors
Only fetch the properties you need. Accessing an unfetched property throws
CNContactPropertyNotFetchedException.
Common Keys
Key
Property
CNContactGivenNameKey
First name
CNContactFamilyNameKey
Last name
CNContactPhoneNumbersKey
Phone numbers array
CNContactEmailAddressesKey
Email addresses array
CNContactPostalAddressesKey
Mailing addresses array
CNContactImageDataKey
Full-resolution contact photo
CNContactThumbnailImageDataKey
Thumbnail contact photo
CNContactBirthdayKey
Birthday date components
CNContactOrganizationNameKey
Company name
Composite Key Descriptors
Use CNContactFormatter.descriptorForRequiredKeys(for:) to fetch all keys needed
for formatting a contact's name.
let nameKeys = CNContactFormatter.descriptorForRequiredKeys(for: .fullName)
let keys: [CNKeyDescriptor] = [nameKeys, CNContactPhoneNumbersKey as CNKeyDescriptor]
Creating and Updating Contacts
Use CNMutableContact to build new contacts and CNSaveRequest to persist changes.
Creating a New Contact
func createContact(givenName: String, familyName: String, phone: String) throws {
let contact = CNMutableContact()
contact.givenName = givenName
contact.familyName = familyName
contact.phoneNumbers = [
CNLabeledValue(
label: CNLabelPhoneNumberMobile,
value: CNPhoneNumber(stringValue: phone)
)
]
let saveRequest = CNSaveRequest()
saveRequest.add(contact, toContainerWithIdentifier: nil) // nil = default container
try store.execute(saveRequest)
}
Updating an Existing Contact
You must fetch the contact with the properties you intend to modify, create a
mutable copy, change the properties, then save.
func updateContactEmail(identifier: String, email: String) throws {
let keys: [CNKeyDescriptor] = [
CNContactEmailAddressesKey as CNKeyDescriptor
]
let contact = try store.unifiedContact(withIdentifier: identifier, keysToFetch: keys)
guard let mutable = contact.mutableCopy() as? CNMutableContact else { return }
mutable.emailAddresses.append(
CNLabeledValue(label: CNLabelWork, value: email as NSString)
)
let saveRequest = CNSaveRequest()
saveRequest.update(mutable)
try store.execute(saveRequest)
}
Deleting a Contact
func deleteContact(identifier: String) throws {
let keys: [CNKeyDescriptor] = [CNContactIdentifierKey as CNKeyDescriptor]
let contact = try store.unifiedContact(withIdentifier: identifier, keysToFetch: keys)
guard let mutable = contact.mutableCopy() as? CNMutableContact else { return }
let saveRequest = CNSaveRequest()
saveRequest.delete(mutable)
try store.execute(saveRequest)
}
Contact Picker
CNContactPickerViewController lets users pick contacts without granting full
Contacts access. The app receives only the selected contact data.
SwiftUI Wrapper
import SwiftUI
import ContactsUI
struct ContactPicker: UIViewControllerRepresentable {
@Binding var selectedContact: CNContact?
func makeUIViewController(context: Context) -> CNContactPickerViewController {
let picker = CNContactPickerViewController()
picker.delegate = context.coordinator
return picker
}
func updateUIViewController(_ uiViewController: CNContactPickerViewController, context: Context) {}
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
final class Coordinator: NSObject, CNContactPickerDelegate {
let parent: ContactPicker
init(_ parent: ContactPicker) {
self.parent = parent
}
func contactPicker(_ picker: CNContactPickerViewController, didSelect contact: CNContact) {
parent.selectedContact = contact
}
func contactPickerDidCancel(_ picker: CNContactPickerViewController) {
parent.selectedContact = nil
}
}
}
Using the Picker
struct ContactSelectionView: View {
@State private var selectedContact: CNContact?
@State private var showPicker = false
var body: some View {
VStack {
if let contact = selectedContact {
Text("\(contact.givenName) \(contact.familyName)")
}
Button("Select Contact") {
showPicker = true
}
}
.sheet(isPresented: $showPicker) {
ContactPicker(selectedContact: $selectedContact)
}
}
}
Filtering the Picker
Use predicates to control which contacts appear and what the user can select.
let picker = CNContactPickerViewController()
// Only show contacts that have an email address
picker.predicateForEnablingContact = NSPredicate(format: "emailAddresses.@count > 0")
// Selecting a contact returns it directly (no detail card)
picker.predicateForSelectionOfContact = NSPredicate(value: true)
Observing Changes
Listen for external contact database changes to refresh cached data.
func observeContactChanges() {
NotificationCenter.default.addObserver(
forName: .CNContactStoreDidChange,
object: nil,
queue: .main
) { _ in
// Refetch contacts -- cached CNContact objects are stale
refreshContacts()
}
}
Common Mistakes
DON'T: Fetch all keys when you only need a name
Over-fetching wastes memory and slows queries, especially for contacts with
large photos.
// WRONG: Fetches everything including full-resolution photos
let keys: [CNKeyDescriptor] = [CNContactCompleteNameKey as CNKeyDescriptor,
CNContactImageDataKey as CNKeyDescriptor,
CNContactPhoneNumbersKey as CNKeyDescriptor,
CNContactEmailAddressesKey as CNKeyDescriptor,
CNContactPostalAddressesKey as CNKeyDescriptor,
CNContactBirthdayKey as CNKeyDescriptor]
// CORRECT: Fetch only what you display
let keys: [CNKeyDescriptor] = [
CNContactGivenNameKey as CNKeyDescriptor,
CNContactFamilyNameKey as CNKeyDescriptor
]
DON'T: Access unfetched properties
Accessing a property that was not in keysToFetch throws
CNContactPropertyNotFetchedException at runtime.
// WRONG: Only fetched name keys, now accessing phone
let keys: [CNKeyDescriptor] = [CNContactGivenNameKey as CNKeyDescriptor]
let contact = try store.unifiedContact(withIdentifier: id, keysToFetch: keys)
let phone = contact.phoneNumbers.first // CRASH
// CORRECT: Include the key you need
let keys: [CNKeyDescriptor] = [
CNContactGivenNameKey as CNKeyDescriptor,
CNContactPhoneNumbersKey as CNKeyDescriptor
]
DON'T: Mutate a CNContact directly
CNContact is immutable. You must call mutableCopy() to get a CNMutableContact.
// WRONG: CNContact has no setter
let contact = try store.unifiedContact(withIdentifier: id, keysToFetch: keys)
contact.givenName = "New Name" // Compile error
// CORRECT: Create mutable copy
guard let mutable = contact.mutableCopy() as? CNMutableContact else { return }
mutable.givenName = "New Name"
DON'T: Skip authorization and assume access
Without calling requestAccess(for:), fetch methods return empty results or throw.
// WRONG: Jump straight to fetch
let contacts = try store.unifiedContacts(matching: predicate, keysToFetch: keys)
// CORRECT: Check or request access first
let granted = try await store.requestAccess(for: .contacts)
guard granted else { return }
let contacts = try store.unifiedContacts(matching: predicate, keysToFetch: keys)
DON'T: Run heavy fetches on the main thread
enumerateContacts performs I/O. Running it on the main thread blocks the UI.
// WRONG: Main thread enumeration
func loadContacts() {
try store.enumerateContacts(with: request) { contact, _ in ... }
}
// CORRECT: Run on a background thread
func loadContacts() async throws -> [CNContact] {
try await Task.detached {
var results: [CNContact] = []
try store.enumerateContacts(with: request) { contact, _ in
results.append(contact)
}
return results
}.value
}
Review Checklist
NSContactsUsageDescriptionadded to Info.plist
requestAccess(for: .contacts)called before fetch or save operations
- Authorization denial handled gracefully (guide user to Settings)
- Only needed
CNKeyDescriptorkeys included in fetch requests
CNContactFormatter.descriptorForRequiredKeys(for:)used when formatting names
- Mutable copy created via
mutableCopy()before modifying contacts
CNSaveRequestused for all create/update/delete operations
- Heavy fetches (
enumerateContacts) run off the main thread
CNContactStoreDidChangeobserved to refresh cached contacts
CNContactPickerViewControllerused when full Contacts access is unnecessary
- Picker predicates set before presenting the picker view controller
- Single
CNContactStoreinstance reused across the app
References
- Extended patterns (multi-select picker, vCard export, search optimization): references/contacts-patterns.md