DiffableDataSource create snapshot

DiffableDataSourceCreateSnapshot.swift

import UIKit

class ViewController: UIViewController {

    var datasource : UITableViewDiffableDataSource<Section, Item>!
    
    var items = [Item]()
    var tommorowItems = [Item]()            
    @IBOutlet weak var tableView: UITableView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        tableView.register(UINib(nibName: "CustomTableViewCell", bundle: nil), forCellReuseIdentifier: "CustomTableViewCell")
        
        self.datasource = UITableViewDiffableDataSource(tableView: tableView, cellProvider: { (tableView, indexPath, item) -> UITableViewCell? in
            let cell = tableView.dequeueReusableCell(withIdentifier: "CustomTableViewCell") as! CustomTableViewCell
            cell.customLabel.text = item.data
            return cell
        })
        
        items.append(Item(id: "1", data: "123"))
        items.append(Item(id: "2", data: "456"))
        items.append(Item(id: "3", data: "789"))
        
        tommorowItems.append(Item(id: "4", data: "123"))
        tommorowItems.append(Item(id: "5", data: "456"))
        tommorowItems.append(Item(id: "6", data: "789"))
        
        let snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
        snapshot.appendSections([Section.today, Section.tomorrow])
        snapshot.appendItems(items, toSection: Section.today)
        snapshot.appendItems(tommorowItems, toSection: Section.tomorrow)
        datasource.apply(snapshot)
        
    }
}