session-ios/SignalUtilitiesKit/GroupUtilities.swift

public enum GroupUtilities {

    public static func getClosedGroupMembers(_ closedGroup: TSGroupThread) -> [String] {
        var result: [String]!
        OWSPrimaryStorage.shared().dbReadConnection.read { transaction in
            result = getClosedGroupMembers(closedGroup, with: transaction)
        }
        return result
    }

    public static func getClosedGroupMembers(_ closedGroup: TSGroupThread, with transaction: YapDatabaseReadTransaction) -> [String] {
        return closedGroup.groupModel.groupMemberIds.filter { member in
            OWSPrimaryStorage.shared().getMasterHexEncodedPublicKey(for: member, in: transaction) == nil // Don't show slave devices
        }
    }

    public static func getClosedGroupMemberCount(_ closedGroup: TSGroupThread) -> Int {
        return getClosedGroupMembers(closedGroup).count
    }

    public static func getClosedGroupMemberCount(_ closedGroup: TSGroupThread, with transaction: YapDatabaseReadTransaction) -> Int {
        return getClosedGroupMembers(closedGroup, with: transaction).count
    }
}