Discover the power of Diffable Data Source in Swift for managing data in table views and collection views with ease and efficiency
Introduction
Diffable Data Source is a powerful feature introduced in iOS 13 that simplifies the process of managing and displaying data in table views and collection views. It provides a new way to manage and update the data in your table view or collection view without having to worry about the underlying implementation details.
Using a Diffable Data Source, you can easily update your table view or collection view with changes to your data, such as additions, deletions, and modifications, in a way that is both efficient and animated. You no longer need to manually manage the state of your data source, which makes your code more reliable, easier to read, and less error-prone.
In this article, we’ll explore how to create a Diffable Data Source in Swift and use it to populate, section, and filter data in a table view or collection view. We’ll also discuss some best practices and tips for working with Diffable Data Sources to help you get the most out of this powerful new feature.
Getting Started
To use a Diffable Data Source in your iOS app, you need to first create a data source object that conforms to the UITableViewDiffableDataSource or UICollectionViewDiffableDataSource protocol. This data source object is responsible for managing the data and providing cells to the table view or collection view.
As the names refer UITableViewDiffableDataSource and UICollectionViewDiffableDataSource corresponds to UITableView and UICollectionView respectively
Here’s an example of how to create a Diffable Data Source for a table view:
class MyTableViewController: UITableViewController {
var dataSource: UITableViewDiffableDataSource<Section, Item>!
override func viewDidLoad() {
super.viewDidLoad()
// Create the data source
dataSource = UITableViewDiffableDataSource(tableView: tableView) { tableView, indexPath, item in
let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath)
cell.textLabel?.text = item.title
return cell
}
// Populate the data source with initial data
var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
snapshot.appendSections([.main])
snapshot.appendItems([Item(title: "Item 1"), Item(title: "Item 2"), Item(title: "Item 3")])
dataSource.apply(snapshot, animatingDifferences: false)
}
}
In this example, we create a new UITableViewDiffableDataSource object by passing in the tableView a closure that creates and configures the cells. We then populate the data source with initial data by creating a new snapshot object, adding sections and items to it, and applying it to the data source using the apply(_:animatingDifferences:) method.
Once you have set up your data source, you can use it to manage your table view or collection view data by adding, deleting, and updating items and sections as needed.
Populating Data
To populate your table view or collection view with data using a Diffable Data Source, you need to create a snapshot object that contains the sections and items you want to display. You can then apply this snapshot to the data source using the apply(_:animatingDifferences:) method.
Here’s an example of how to populate a table view with data using a Diffable Data Source:
// Define the sections and items
enum Section {
case main
}
struct Item: Hashable {
let id = UUID()
let title: String
}
class MyTableViewController: UITableViewController {
var dataSource: UITableViewDiffableDataSource<Section, Item>!
override func viewDidLoad() {
super.viewDidLoad()
// Create the data source
dataSource = UITableViewDiffableDataSource(tableView: tableView) { tableView, indexPath, item in
let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath)
cell.textLabel?.text = item.title
return cell
}
// Populate the data source with initial data
var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
snapshot.appendSections([.main])
snapshot.appendItems([
Item(title: "Item 1"),
Item(title: "Item 2"),
Item(title: "Item 3")
])
dataSource.apply(snapshot, animatingDifferences: false)
}
}
In this example, we define a Section enum and an Item struct that contains the data we want to display. We then create a data source object that uses these types and configure it with a cell creation closure.
We then create a new snapshot object, add a single section to it using the .main case of the Section enum, and add some items to it. Finally, we apply the snapshot to the data source using the apply(_:animatingDifferences:) method, which updates the table view with the new data.
You can repeat this process as needed to update the data in your table view or collection view with changes, additions, and deletions to your data.
Sectioning Data
You can easily section the data displayed in your table view or collection view using Diffable Data Source in Swift. To do this, you need to create a new snapshot that contains the sections and items you want to display and apply it to the data source.
Here’s an example of how to section the data displayed in a table view using a Diffable Data Source:
class MyTableViewController: UITableViewController {
var dataSource: UITableViewDiffableDataSource<Section, Item>!
var allItems: [Item] = []
override func viewDidLoad() {
super.viewDidLoad()
// Create the data source
dataSource = UITableViewDiffableDataSource(tableView: tableView) { tableView, indexPath, item in
let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath)
cell.textLabel?.text = item.title
return cell
}
// Populate the data source with the initial data
allItems = [
Item(title: "Item 1", category: "Category 1"),
Item(title: "Item 2", category: "Category 1"),
Item(title: "Item 3", category: "Category 2")
]
applySnapshot()
}
func applySnapshot() {
var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
let categories = Set(allItems.map { $0.category })
let sections = categories.sorted().map { category -> Section in
return Section(title: category)
}
snapshot.appendSections(sections)
for section in sections {
let items = allItems.filter { $0.category == section.title }
snapshot.appendItems(items, toSection: section)
}
dataSource.apply(snapshot, animatingDifferences: true)
}
}
In this example, we create a Section struct that represents a section in the table view, with a title property that represents the section’s title. We then create an Item struct that contains the data we want to display, along with a category property that we will use to group the items into sections.
We create a UITableViewDiffableDataSource and configure it with a cell creation closure as usual. We then create an allItems array that contains all the items we want to display, along with their categories.
To section the data, we start by creating a new snapshot and getting the unique categories from the allItems array. We then create a new Section object for each category, sorted in alphabetical order, and append them to the snapshot using the appendSections(_:) method.
We then iterate over each section and filter the allItems array to get the items that belong to that section’s category. We append these items to the snapshot using the appendItems(_:toSection:) method, which adds the items to the specified section.
Finally, we apply the snapshot to the data source using the apply(_:animatingDifferences:) method, which updates the table view with the new sections and items.
Filtering Data
You can easily filter the data displayed in your table view or collection view using Diffable Data Source in Swift. To do this, you need to create a new snapshot that contains only the items that match your filter criteria and apply it to the data source.
Here’s an example of how to filter the data displayed in a table view using a Diffable Data Source:
class MyTableViewController: UITableViewController {
var dataSource: UITableViewDiffableDataSource<Section, Item>!
var allItems: [Item] = []
override func viewDidLoad() {
super.viewDidLoad()
// Create the data source
dataSource = UITableViewDiffableDataSource(tableView: tableView) { tableView, indexPath, item in
let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath)
cell.textLabel?.text = item.title
return cell
}
// Populate the data source with the initial data
allItems = [
Item(title: "Item 1"),
Item(title: "Item 2"),
Item(title: "Item 3")
]
applySnapshot(items: allItems)
}
func applySnapshot(items: [Item]) {
var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
snapshot.appendSections([.main])
snapshot.appendItems(items)
dataSource.apply(snapshot, animatingDifferences: true)
}
}
// MARK: - UISearchBarDelegate
extension MyTableViewController: UISearchBarDelegate {
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
let filteredItems = allItems.filter { item in
searchText.isEmpty || item.title.localizedStandardContains(searchText)
}
applySnapshot(items: filteredItems)
}
}
In this example, we create a UISearchBar and implement the searchBar(_:textDidChange:) delegate method to filter the data displayed in the table view. We start by filtering the allItems array based on the search text, and then call a helper method applySnapshot(items:) that creates a new snapshot containing only the filtered items and applies it to the data source.
The applySnapshot(items:) method is responsible for creating a new snapshot with the filtered items and applying it to the data source. We start by creating a new snapshot, adding a single section to it, and appending the filtered items. Finally, we apply the snapshot to the data source using the apply(_:animatingDifferences:) method with animatingDifferences set to true to animate the changes.
You can adapt this example to filter the data displayed in a collection view by changing the type of the data source object to UICollectionViewDiffableDataSource.
Differences from Traditional Data Sources
Using Diffable Data Source in Swift offers several advantages over traditional data sources such as UITableViewDataSource and UICollectionViewDataSource. One major advantage is that Diffable Data Source manages the data and the updates to it, which greatly simplifies the code required to display and update the data in your table view or collection view.
With Diffable Data Source, you don’t have to manually track the state of your data, including its ordering, filtering, and sectioning. Instead, you can simply create a new snapshot that represents the current state of your data, and apply it to the data source using the apply(_:animatingDifferences:) method. Diffable Data Source then takes care of updating the table view or collection view to reflect the changes in the snapshot, including adding, deleting, and moving items, as well as animating the changes for a smooth user experience.
Another advantage of Diffable Data Source is that it provides type safety and compiler-checked correctness. The data types used in the data source, such as section and item identifiers, are defined at compile time, which helps prevent common runtime errors such as typos or incorrect types. Additionally, Diffable Data Source uses a declarative syntax, which makes it easier to reason about and modify your data source code.
In contrast, traditional data sources such as UITableViewDataSource and UICollectionViewDataSource require you to manually manage the state of your data, including its ordering, filtering, and sectioning, which can be error-prone and time-consuming. Additionally, traditional data sources often rely on mutable states, which can make it harder to reason about the behavior of your code and can lead to subtle bugs.
Overall, Diffable Data Source offers a simpler, safer, and more powerful way to manage the data displayed in your table view or collection view in Swift.
// Example using UITableViewDataSource
class MyTableViewController: UITableViewController {
var data: [String] = ["Apple", "Banana", "Cherry", "Durian"]
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return data.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath)
cell.textLabel?.text = data[indexPath.row]
return cell
}
}
// Example using Diffable Data Source
class MyDiffableTableViewController: UITableViewController {
typealias Item = String
typealias Section = Int
var dataSource: UITableViewDiffableDataSource<Section, Item>!
override func viewDidLoad() {
super.viewDidLoad()
dataSource = UITableViewDiffableDataSource(tableView: tableView) { tableView, indexPath, item in
let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath)
cell.textLabel?.text = item
return cell
}
var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
snapshot.appendSections([0])
snapshot.appendItems(["Apple", "Banana", "Cherry", "Durian"])
dataSource.apply(snapshot, animatingDifferences: false)
}
}
As you can see, using Diffable Data Source is much more concise and declarative than using UITableViewDataSource. In the MyDiffableTableViewController example, we define the types for our data source using type aliases and create a new instance of UITableViewDiffableDataSource that uses these types. We then create a snapshot of our data using the NSDiffableDataSourceSnapshot class and apply it to the data source using the apply(_:animatingDifferences:) method.
In contrast, the MyTableViewController example using UITableViewDataSource requires more code to manage the state of the data, including an array to hold the data and manual index manipulation to update the table view.
(Bonus) Tips and Best Practices
-
Use a clear and consistent data model: A Diffable Data Source relies on a clear and consistent data model to work effectively. Make sure that your data model is well-defined and that each item in the data source has a unique identifier.
-
Use appropriate identifiers for items: When using a Diffable Data Source, each item in the data source needs a unique identifier. In some cases, this might be an ID number or a unique string. Make sure that your identifiers are unique and consistent across your data source.
-
Use the snapshot API to update your data source: The snapshot API is a powerful tool for updating your data source. Use it to create new snapshots that reflect changes to your data, and then apply those snapshots to your Diffable Data Source. This will help ensure that your table view or collection view is always up-to-date.
-
Consider performance implications: While Diffable Data Sources are designed to be performant, they can still be affected by large or complex data sets. If you’re working with a large data set, consider using background threads to create or update snapshots, and be mindful of how you’re filtering or sorting your data.
-
Test your Diffable Data Source thoroughly: When using Diffable Data Sources, it’s important to test your code thoroughly to ensure that it’s working as expected. Use Xcode’s built-in debugging tools, such as breakpoints and console logs, to identify and troubleshoot any issues that arise.
By following these tips and best practices, you can ensure that your Diffable Data Sources are well-designed, performant, and reliable.
Conclusion
Diffable Data Source is a powerful and easy-to-use framework for managing and displaying data in table views and collection views in Swift. It provides a declarative syntax and type safety, making it easier to reason about and modify your code. Additionally, it simplifies the process of managing the state of your data, including ordering, filtering, and sectioning.
By using Diffable Data Source in your Swift projects, you can save time and reduce the likelihood of errors in your code. With its built-in support for animating changes to your data, Diffable Data Source also provides a seamless and visually pleasing user experience for your table views and collection views.
Overall, if you’re looking for a modern and efficient way to manage and display data in your table views and collection views in Swift, Diffable Data Source is a great choice. Whether you’re building a simple app or a complex data-driven app, Diffable Data Source can help you achieve your goals with less code and fewer bugs.
I hope this article helps you, I’ll appreciate it if you can share it and #HappyCoding👨💻.
