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UITableView Diffable Data Source Tutorial

Jul 20, 2024

UITableView Diffable Data Source

Introduction

  • Diffable Data Source: A way to supply an object to UITableView or UICollectionView allowing model/data diffing and UI updates with animations.
  • Automatically applies a snapshot to update data/UI.

Setup

  1. Create a New Project
    • Use App template, name it DiffableDataSource, use Swift, Storyboard, and UIKit.
  2. Embed Navigation Controller
    • Use Editor -> Embed in -> Navigation Controller in Storyboard.

Creating the Table View

  • Anonymous closure pattern to initialize the table view.
  • Register cell: tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell").
  • Set delegate = self (No need to assign dataSource here).

Diffable Data Source Initialization

  1. Create Models
    • Section using enum.
    • Data model (Fruit) using struct conforming to Hashable.
  2. Declare Diffable Data Source
    • var dataSource: UITableViewDiffableDataSource<Section, Fruit>?

Adding UI Elements

  1. Add Plus Button
    • Navigation bar button to add items.
  2. Present Action Sheet
    • UIAlertController with multiple options to select and add fruits to the table view.

Snapshot

  • Create and apply snapshot to data source:
var snapshot = NSDiffableDataSourceSnapshot<Section, Fruit>() snapshot.appendSections([.main]) snapshot.appendItems(fruits, toSection: .main) dataSource.apply(snapshot, animatingDifferences: true)

Handling Data Updates

  1. Button Action
    • Append selected fruit to the data array and update the data source.
  2. Implement updateDataSource method
    • Apply snapshot to update table view with animations.

Selection Handling

  • Implement UITableViewDelegate method:
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { tableView.deselectRow(at: indexPath, animated: true) if let fruit = dataSource.itemIdentifier(for: indexPath) { print(fruit.title) } }

Important Notes

  • Ensure models are hashable and unique to avoid crashes.
  • Diffable Data Source simplifies code, removing the need for reloadData calls.
  • iOS 13 and up only.

Conclusion

  • Simplifies updating UIs and handling data changes.
  • Automatically handles animations for data changes.

Action Items

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