IGListKit/Examples/Examples-iOS/IGListKitExamples/ViewControllers/SearchViewController.swift

/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

import IGListKit
import UIKit

final class SearchViewController: UIViewController, ListAdapterDataSource, SearchSectionControllerDelegate {

    lazy var adapter: ListAdapter = {
        return ListAdapter(updater: ListAdapterUpdater(), viewController: self)
    }()
    let collectionView = UICollectionView(frame: .zero, collectionViewLayout: UICollectionViewFlowLayout())
    lazy var words: [String] = {
        // swiftlint:disable:next
        let str = "Humblebrag skateboard tacos viral small batch blue bottle, schlitz fingerstache etsy squid. Listicle tote bag helvetica XOXO literally, meggings cardigan kickstarter roof party deep v selvage scenester venmo truffaut. You probably haven't heard of them fanny pack austin next level 3 wolf moon. Everyday carry offal brunch 8-bit, keytar banjo pinterest leggings hashtag wolf raw denim butcher. Single-origin coffee try-hard echo park neutra, cornhole banh mi meh austin readymade tacos taxidermy pug tattooed. Cold-pressed +1 ethical, four loko cardigan meh forage YOLO health goth sriracha kale chips. Mumblecore cardigan humblebrag, lo-fi typewriter truffaut leggings health goth."
        var unique = Set<String>()
        var words = [String]()
        let range = str.startIndex ..< str.endIndex
        str.enumerateSubstrings(in: range, options: .byWords) { (substring, _, _, _) in
            guard let substring = substring else { return }
            if !unique.contains(substring) {
                unique.insert(substring)
                words.append(substring)
            }
        }
        return words
    }()
    var filterString = ""
    let searchToken: NSNumber = 42

    override func viewDidLoad() {
        super.viewDidLoad()
        view.addSubview(collectionView)
        adapter.collectionView = collectionView
        adapter.dataSource = self
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        collectionView.frame = view.bounds
    }

    // MARK: ListAdapterDataSource

    func objects(for listAdapter: ListAdapter) -> [ListDiffable] {
        guard filterString != "" else { return [searchToken] + words.map { $0 as ListDiffable } }
        return [searchToken] + words.filter { $0.lowercased().contains(filterString.lowercased()) }.map { $0 as ListDiffable }
    }

    func listAdapter(_ listAdapter: ListAdapter, sectionControllerFor object: Any) -> ListSectionController {
        if let obj = object as? NSNumber, obj == searchToken {
            let sectionController = SearchSectionController()
            sectionController.delegate = self
            return sectionController
        } else {
            return LabelSectionController()
        }
    }

    func emptyView(for listAdapter: ListAdapter) -> UIView? {
        return nil
    }

    // MARK: SearchSectionControllerDelegate

    func searchSectionController(_ sectionController: SearchSectionController, didChangeText text: String) {
        filterString = text
        adapter.performUpdates(animated: true, completion: nil)
    }

}