CNContact fetching should be faster - swift

Question

I am fetching contact from CNContact and it took .30 seconds to show thousands of contact in UI. My client want me to reduce time upto 0.01 second. He gave me example of Telegram app. Can any one help
Ex Code :
typealias ContactsHandler = (_ contacts : [CNContact] , _ error : NSError?) -> Void
extension CDContactsPickerVC {
func getContacts(_ completion: #escaping ContactsHandler) {
if contactsStore == nil {
//ContactStore is control for accessing the Contacts
contactsStore = CNContactStore()
}
let error = NSError(domain: "CDContactPickerErrorDomain", code: 1, userInfo: [NSLocalizedDescriptionKey: "No Contacts Access"])
switch CNContactStore.authorizationStatus(for: CNEntityType.contacts) {
case CNAuthorizationStatus.denied, CNAuthorizationStatus.restricted:
//User has denied the current app to access the contacts.
let productName = Bundle.main.infoDictionary!["CFBundleName"]!
let alert = UIAlertController(title: "Unable to access contacts", message: "\(productName) does not have access to contacts. Kindly enable it in privacy settings ", preferredStyle: UIAlertControllerStyle.alert)
let okAction = UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: { action in
completion([], error)
})
alert.addAction(okAction)
self.present(alert, animated: true, completion: nil)
case CNAuthorizationStatus.notDetermined:
//This case means the user is prompted for the first time for allowing contacts
contactsStore?.requestAccess(for: CNEntityType.contacts, completionHandler: { (granted, error) -> Void in
//At this point an alert is provided to the user to provide access to contacts. This will get invoked if a user responds to the alert
if (!granted ){
DispatchQueue.main.async(execute: { () -> Void in
completion([], error! as NSError?)
})
}
else{
self.getContacts(completion)
}
})
case CNAuthorizationStatus.authorized:
//Authorization granted by user for this app.
var contactsArray = [CNContact]()
let contactFetchRequest = CNContactFetchRequest(keysToFetch: allowedContactKeys())
do {
try contactsStore?.enumerateContacts(with: contactFetchRequest, usingBlock: { (contact, stop) -> Void in
//Ordering contacts based on alphabets in firstname
contactsArray.append(contact)
var key: String = "#"
//If ordering has to be happening via family name change it here.
if let firstLetter = contact.givenName[0..<1] , firstLetter.containsAlphabets() {
key = firstLetter.uppercased()
}
var contacts = [CNContact]()
if let segregatedContact = self.orderedContacts[key] {
contacts = segregatedContact
}
var identifierArray = [String]()
for contactDict in self.orderedContacts {
let contactArray = contactDict.value as [CNContact]
for cnObj in contactArray {
identifierArray.append(cnObj.identifier)
}
}
if identifierArray.contains(contact.identifier) {
// do nothing
}else {
contacts.append(contact)
self.orderedContacts[key] = contacts
}
})
self.sortedContactKeys = Array(self.orderedContacts.keys).sorted(by: <)
if self.sortedContactKeys.first == "#" {
self.sortedContactKeys.removeFirst()
self.sortedContactKeys.append("#")
}
completion(contactsArray, nil)
}
//Catching exception as enumerateContactsWithFetchRequest can throw errors
catch let error as NSError {
print(error.localizedDescription)
}
}
}
func allowedContactKeys() -> [CNKeyDescriptor]{
//We have to provide only the keys which we have to access. We should avoid unnecessary keys when fetching the contact. Reducing the keys means faster the access.
return [CNContactNamePrefixKey as CNKeyDescriptor,
CNContactGivenNameKey as CNKeyDescriptor,
CNContactFamilyNameKey as CNKeyDescriptor,
CNContactPhoneNumbersKey as CNKeyDescriptor,
CNContactEmailAddressesKey as CNKeyDescriptor,
]
}
// MARK: - Contact Operations
open func reloadContacts() {
DispatchQueue.global(qos: .background).async {
self.getContacts( {(contacts, error) in
if (error == nil) {
DispatchQueue.main.async(execute: {
self.emptyContactLabel.isHidden = contacts.count > 0 ? true : false
self.tableView.reloadData()
})
self.updateContactsInLocalDB(contacts: contacts)
}
})
}
}