README.md

flutter_callkit_voximplant + CallKit CallDirectory App Extension

Apps can create a Call Directory app extension to identify and block incoming callers by their phone number.

How to implement Call Blocking and Identification

1. Create a Call Directory App Extension

An iOS CallDirectory App Extension must be created and implemented, an example of implementation can be found here

You can create a Call Directory extension for your containing app by adding a new project target and selecting the Call Directory Extension template under Application Extensions in XCode.

More on iOS app extensions

2. Create an iOS located data storage for the phone numbers

Data storage is needed to share numbers between the app and CallDirectory extension, a basic example of the UserDefaults as the storage implementation can be found here

3. Connect the data storage with the extension

In the app extension use the data storage to retrieve blocked/identified numbers from there and pass them to CXCallDirectoryExtensionContext.

@UserDefault("blockedNumbers", defaultValue: [])
private var blockedNumbers: [BlockableNumber]

@UserDefault("identifiedNumbers", defaultValue: [])
private var identifiedNumbers: [IdentifiableNumber]

func updateNumbers() {
    blockedNumbers.forEach {
        context.addBlockingEntry(withNextSequentialPhoneNumber: $0.number)
    }

    identifiedNumbers.forEach {
        context.addIdentificationEntry(
            withNextSequentialPhoneNumber: $0.number,
            label: $0.label
        )
    }
}

4. Connect the data storage with the CallKit plugin

In the iOS native code connect the data storage with the plugin to receive Flutter method calls (get/add/remove numbers). Assign FlutterCallkitPlugin instance closure-properties to functions that interact with the storage so that link the storage to the plugin.

// the plugin
private let callKitPlugin = FlutterCallkitPlugin.sharedInstance

// the storage
@UserDefault("blockedNumbers", defaultValue: [])
private var blockedNumbers: [BlockableNumber]

// the connection with the plugin
func connectStorage() {
    callKitPlugin.getBlockedPhoneNumbers = { [weak self] in
        guard let self = self else { return [] }
        return self.blockedNumbers.compactMap {
            if $0.isRemoved {
                return nil
            } else {
                return FCXCallDirectoryPhoneNumber(number: $0.number)
            }
        }
    }

    callKitPlugin.didAddBlockedPhoneNumbers = { [weak self] numbers in
        guard let self = self else { return }
        self.blockedNumbers.append(
            contentsOf: numbers.map { BlockableNumber(blockableNumber: $0) }
        )
        self.blockedNumbers.sort()
    }

    callKitPlugin.didRemoveBlockedPhoneNumbers = { [weak self] numbers in
        guard let self = self else { return }
        self.blockedNumbers = self.blockedNumbers.map { number in
            if numbers.contains(where: { $0.number == number.number }) {
                return number.copyWithRemovalMark
            } else {
                return number
            }
        }
    }
}

5. Use FCXPlugin in Flutter code to get/add/remove identified/blocked numbers

• Get numbers

Call FCXPlugin.get methods to retrieve blocked/identified numbers from the storage in the iOS native code.

Future<List<FCXCallDirectoryPhoneNumber>> getBlockedNumbers() async {
  return await _plugin.getBlockedPhoneNumbers();
}
Future<List<FCXIdentifiablePhoneNumber>> getIdentifiedNumbers() async {
  return await _plugin.getIdentifiablePhoneNumbers();
}

• Add or remove numbers

Call FCXPlugin.add/remove methods to send blocked/identified numbers from the Flutter to the iOS native code and save them in the storage.

Future<void> addBlockedNumber(String number) async {
  int num = int.parse(number);
  await _plugin.addBlockedPhoneNumbers(
    [FCXCallDirectoryPhoneNumber(num)],
  );
}

Future<void> removeBlockedNumber(String number) async {
  int num = int.parse(number);
  await _plugin.removeBlockedPhoneNumbers(
    [FCXCallDirectoryPhoneNumber(num)],
  );
}

Future<void> addIdentifiedNumber(String number, String id) async {
  int num = int.parse(number);
  var phone = FCXIdentifiablePhoneNumber(num, label: id);
  await _plugin.addIdentifiablePhoneNumbers([phone]);
}

Future<void> removeIdentifiedNumber(int number) async {
  await _plugin.removeIdentifiablePhoneNumbers(
    [FCXCallDirectoryPhoneNumber(number)],
  );
}

6. Reload extension to request extension data reload

After updating the storage, to let the changes take effect, CallDirectory App Extension must be reloaded, a request to reload might be sent via FCXCallDirectoryManager.reloadExtension method.

Future<void> reloadExtension() async {
  await FCXCallDirectoryManager.reloadExtension(_extensionID);
}

Reference

iOS CallKit Framework Documentation by Apple

App Extension Programming Guide by Apple

Example app by Voximplant