ContactsViewController.swift

//
//  ContactsViewController.swift
//  ContactsApp
//
//  Created by User on 3/13/20.
//  Copyright © 2020 jheisecke. All rights reserved.
//

import UIKit
import ContactsUI

class ContactsViewController: UIViewController {
    
    @IBOutlet weak var contactsTable: UITableView!
    
    var contacts = [CNContact]()
    var contactsBackup = [CNContact]()
    let contactStore = CNContactStore()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        importContacts()
        contactsTable.tableFooterView = UIView(frame: .zero)
    }
    
    func importContacts() {
        
        let keys = [CNContactFormatter.descriptorForRequiredKeys(for: .fullName), CNContactEmailAddressesKey, CNContactPhoneNumbersKey, CNContactImageDataKey, CNContactImageDataAvailableKey] as [Any]
        let request = CNContactFetchRequest( keysToFetch: keys as! [CNKeyDescriptor])
        request.sortOrder = CNContactSortOrder.givenName
        do {
            try self.contactStore.enumerateContacts(with: request) {
                (contact, stop) in
                // Array containing all unified contacts from everywhere
                self.contacts.append(contact)
            }
        }
        catch {
            print("unable to fetch contacts")
        }

        print(contacts)
    }
    
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if let singleContactVC = segue.destination as? SingleContactViewController {
            if let selectedCnt = sender as? CNContact {
                singleContactVC.selectedContact = selectedCnt
            }
        }
    }
}
extension ContactsViewController: UITableViewDelegate, UITableViewDataSource {
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return contacts.count
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "contactName")!
        cell.textLabel?.text = "\(contacts[indexPath.row].givenName) \(contacts[indexPath.row].familyName)"
        return cell
    }
    
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let selectedContact = contacts[indexPath.row]
        performSegue(withIdentifier: "gotocontact", sender: selectedContact)
    }
    
    func tableView(_ tableView: UITableView, estimatedHeightForHeaderInSection section: Int) -> CGFloat {
        return 40
    }
    
    func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        let button = UIButton(type: .system)
        button.setTitle("Λ", for: .normal)
        button.setTitleColor(.black, for: .normal)
        button.titleLabel?.font = UIFont.boldSystemFont(ofSize: 15)
        button.backgroundColor = .systemGray4
        button.addTarget(self, action: #selector(closeSection), for: .touchUpInside)
        
        return button//ʌΛ
    }
    
    @objc func closeSection() {
        contactsBackup = contacts
        let section = 0
        
        var indexPaths = [IndexPath]()
        for row in contacts.indices {
            let indexPath = IndexPath(row: row, section: section)
            indexPaths.append(indexPath)
        }
        contacts.removeAll()
        contactsTable.reloadData()
    }
}