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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