DiffableDataSources

A library for backporting UITableView/UICollectionViewDiffableDataSource.

Apple has announced a diffable data source at WWDC 2019.
It's a great API that easily updating our table view and collection view items using automatic diffing.
However, it's a little while before we can use it in a production service.
That because it requires the latest OS to use.
DiffableDataSources make it possible to introduce almost the same functionality from now on.

Uses a sophisticated open source DifferenceKit for the algorithm engine.
It's extremely fast and completely avoids synchronization bugs, exceptions, and crashes.

Difference from the Official

Spec

  • Supports iOS 9.0+ / macOS 10.11+ / tvOS 9.0+
  • Open sourced algorithm.
  • Duplicate sections or items are allowed.
  • Using performBatchUpdates for diffing updates.

Namings

DiffableDataSources have different class names to avoid conflicts with the official API.
Correspondence table is below.

Official Backported
NSDiffableDataSourceSnapshot DiffableDataSourceSnapshot
UITableViewDiffableDataSource TableViewDiffableDataSource
UICollectionViewDiffableDataSource CollectionViewDiffableDataSource
NSCollectionViewDiffableDataSource CocoaCollectionViewDiffableDataSource

Getting Started

Build Project

$ git clone https://github.com/ra1028/DiffableDataSources.git
$ cd DiffableDataSources/
$ make setup
$ open DiffableDataSources.xcworkspace

Basic Usage

First, define the type representing section.
It should conforms to Hashable for identifies from the all sections.
Type of enum can used conveniently befause it conforms Hashable by default.

enum Section {
    case main
}

Then, define the item type conforms to Hashable.

struct User: Hashable {
    var name: String
}

Create a data source object, it will be set to table view automatically.
You should dequeue the non nil cells via closure.

final class UsersViewController: UIViewController {
    let tableView: UITableView = ...

    lazy var dataSource = TableViewDiffableDataSource<Section, User>(tableView: tableView) { tableView, indexPath, user in
        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
        cell.textLabel?.text = user.name
        return cell
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell")
    }
}

Manages and updates the data sources intuitively by intermediating DiffableDataSourceSnapshot.
The UI isn't updated until you apply the edited snapshot object.
Update the UI with diffing animation automatically calculated by applying an edited snapshot.

let users = [
    User(name: "Steve Jobs"),
    User(name: "Stephen Wozniak"),
    User(name: "Tim Cook"),
    User(name: "Jonathan Ive")
]

let snapshot = DiffableDataSourceSnapshot<Section, User>()
snapshot.appendSections([.main])
snapshot.appendItems(users)

dataSource.apply(snapshot)

Check the documentation for more detailed API.

[See More Usage]

Requirements

  • Swift 5.0+
  • iOS 9.0+
  • macOS 10.11+
  • tvOS 9.0+

Installation

CocoaPods

Add the following to your Podfile:

pod 'DiffableDataSources'

Carthage

Add the following to your Cartfile:

github "ra1028/DiffableDataSources"

Swift Package Manager

Add the following to the dependencies of your Package.swift:

.package(url: "https://github.com/ra1028/DiffableDataSources.git", from: "x.x.x")

GitHub