The best way to Use SwiftData in UIKit Apps

In iOS 17, Apple launched a brand new framework known as SwiftData to interchange the Core Knowledge framework. Earlier, we’ve written an introductory tutorial about SwiftData and confirmed you easy methods to pair SwiftData with SwiftUI.

Whereas there are quite a few studying assets out there for utilizing SwiftData with SwiftUI, some readers have talked about that discovering complete guides for integrating SwiftData into UIKit apps will be difficult. On this tutorial, we are going to delve into the method of leveraging the capabilities of SwiftData throughout the UIKit framework.

A Fast Introduction about SwiftData

To begin off, let’s take a quick tour of the SwiftData framework. It’s necessary to grasp that SwiftData shouldn’t be mistaken for a database itself. As an alternative, it’s a framework constructed upon Core Knowledge, particularly developed to help builders in successfully managing and interacting with knowledge saved persistently. Whereas the default persistent retailer utilized by iOS is usually the SQLite database, it’s price noting that persistent shops can are available numerous types. For example, Core Knowledge can be employed to handle knowledge saved in a neighborhood file, akin to an XML file. This flexibility permits builders to decide on probably the most appropriate persistent retailer for his or her particular necessities.

Whether or not you go for Core Knowledge or the SwiftData framework, each instruments purpose to simplify the intricacies of the underlying persistent retailer for builders. Take the SQLite database, for instance. With SwiftData, there’s no have to concern your self with establishing database connections or delving into SQL queries to retrieve knowledge information. As an alternative, builders can concentrate on using user-friendly APIs and Swift Macros, akin to @Mannequin, to effectively handle knowledge inside their functions. This abstraction permits for a extra streamlined and intuitive knowledge administration expertise.

If in case you have used Core Knowledge earlier than, you could do not forget that it’s a must to create a knowledge mannequin (with a file extension .xcdatamodeld) utilizing a knowledge mannequin editor for knowledge persistence. With the discharge of SwiftData, you now not want to try this. SwiftData streamlines the entire course of with macros, one other new Swift characteristic in iOS 17. Say, for instance, you already outline a mannequin class for Track as follows:

class Track {
  var title: String
  var artist: String
  var album: String
  var style: String
  var score: Double
}

To make use of SwiftData, the brand new @Mannequin macro is the important thing for storing persistent knowledge utilizing SwiftUI. As an alternative of constructing the info mannequin with mannequin editor, SwiftData simply requires you to annotate the mannequin class with the @Mannequin macro like this:

@Mannequin class Track {
  var title: String
  var artist: String
  var album: String
  var style: String
  var score: Double
}

That is the way you outline the schema of the info mannequin in code. With this easy key phrase, SwiftData robotically allows persistence for the info class and gives different knowledge administration functionalities akin to iCloud sync. Attributes are inferred from properties and it helps primary worth sorts akin to Int and String.

SwiftData permits you to customise how your schema is constructed utilizing property metadata. You may add uniqueness constraints through the use of the @Attribute annotation, and delete propagation guidelines with the @Relationship annotation. If there are particular properties you don’t want included, you need to use the @Transient macro to inform SwiftData to exclude them. Right here is an instance:

@Mannequin class Album {
  @Attribute(.distinctive) var identify: String
  var artist: String
  var style: String

  // The cascade relationship instructs SwiftData to delete all 
    // songs when the album is deleted.
  @Attribute(.cascade) var songs: [Song]? = []
}

To drive the info persistent operations, there are two key objects of SwiftData that you have to be aware of: ModelContainer and ModelContext. The ModelContainer serves because the persistent backend in your mannequin sorts. To create a ModelContainer, you merely have to instantiate an occasion of it.

// Fundamental
let container = attempt ModelContainer(for: [Song.self, Album.self])

// With configuration
let container = attempt ModelContainer(for: [Song.self, Album.self], 
                                    configurations: ModelConfiguration(url: URL("path"))))

In UIKit, you’ll be able to instantiate the context for a given mannequin containers like this:

let context = ModelContext(modelContainer)

With the context, you’re able to fetch knowledge. You should utilize the brand new #Predicate macro to construct predicates. Right here is an instance:

// Specify all of the songs whose style is "Pop"
let songPredicate = #Predicate { $0.style == "pop" }

When you outline the standards for fetching, you need to use the FetchDescriptor and inform the mannequin context to fetch the info.

let descriptor = FetchDescriptor(predicate: songPredicate)

let songs = attempt context.fetch(descriptor)

To insert merchandise within the persistent retailer, you’ll be able to name the insert methodology of the mannequin context and go it the mannequin objects to insert.

modelContext.insert(tune)

Equally, you’ll be able to delete the merchandise through the mannequin context like this:

modelContext.delete(tune)

This serves as a quick introduction to SwiftData. If you happen to’re nonetheless feeling not sure about easy methods to make the most of SwiftData, there’s no want to fret. You’ll acquire a transparent understanding of its utilization as we’ll construct a easy To-do app utilizing UIKit and SwiftData.

Constructing a Easy To-do App with SwiftData and UIKit

I’ve already developed a primary to-do app utilizing UIKit. Nonetheless, the present implementation solely shops the to-do gadgets in reminiscence, which implies the info shouldn’t be persistent. To be able to deal with this limitation, our subsequent step is to switch the app and change from utilizing in-memory arrays to leveraging the facility of SwiftData for storing the to-do gadgets in a database. This enhancement will be sure that the to-do gadgets are saved persistently, permitting customers to entry them even after closing the app.

For demo goal, the present model of this app doesn’t present the performance for customers so as to add their very own to-do gadgets. As an alternative, customers can solely add a random to-do merchandise by tapping the “+” button. Nonetheless, customers can nonetheless modify the standing of the prevailing merchandise and delete it by swiping.

Utilizing @Mannequin for the mannequin class

The in-memory model of the app already defines a struct for ToDoItem:

struct ToDoItem: Identifiable, Hashable {
    var id: UUID
    var identify: String
    var isComplete: Bool

    init(id: UUID = UUID(), identify: String = "", isComplete: Bool = false) {
        self.id = id
        self.identify = identify
        self.isComplete = isComplete
    }
}

To make use of SwiftData, we are able to convert this struct to class and annotate it with the @Mannequin macro like this:

import SwiftData

@Mannequin class ToDoItem: Identifiable, Hashable {
    var id: UUID
    var identify: String
    var isComplete: Bool

    init(id: UUID = UUID(), identify: String = "", isComplete: Bool = false) {
        self.id = id
        self.identify = identify
        self.isComplete = isComplete
    }
}

As you’ll be able to see, the one factor that we have to do to make a category work with SwiftData is to prefix it with @Mannequin. SwiftData then robotically allows persistence for the info class.

Saving To-Do Objects into Database

Within the demo app, we’ve the ToDoTableViewController class to deal with the rendering of the to-do desk view, in addition to, the random creation of the to-do gadgets. To handle knowledge with SwiftData, we first create a variable to carry the mannequin container:

var container: ModelContainer?

Within the viewDidLoad methodology, we are able to add the next line of code to instantiate the mannequin container:

container = attempt? ModelContainer(for: ToDoItem.self)

For including a random to-do merchandise, the demo app already had a way named addToDoItem:

@IBAction func addToDoItem(sender: UIBarButtonItem) {
    todoItems.append(generateRandomTodoItem())
    updateSnapshot(animatingChange: true)
}

We known as up the generateRandomTodoItem methodology to get a to-do merchandise and append it to the todoItems array. Then we name up the updateSnapshot methodology to replace the desk view.

To be able to save the to-do merchandise completely, we are able to exchange the code like this:

@IBAction func addToDoItem(sender: UIBarButtonItem) {
    container?.mainContext.insert(generateRandomTodoItem())
    fetchToDoItems()
}

As an alternative of merely including the to-do merchandise to the array, we make the most of the insert methodology of the container’s context to save lots of the merchandise into the inner database.

Fetching Knowledge from Database

The implementation of the fetchToDoItems methodology is pending in the meanwhile. To retrieve knowledge from the database, we have to create an occasion of FetchDescriptor. This enables us to specify the info kind we wish to retrieve and outline any particular search standards if crucial. By using the FetchDescriptor, we are able to successfully retrieve the specified knowledge from the database. After establishing the fetch descriptor object, we are able to proceed to name the fetch methodology of the container’s context and supply the descriptor as an argument. SwiftData will then make the most of this data to retrieve the to-do gadgets accordingly from the database.

Insert the next code snippet to create the fetchToDoItems methodology:

func fetchToDoItems() {
    let descriptor = FetchDescriptor()

    todoItems = (attempt? container?.mainContext.fetch(descriptor)) ?? []

    updateSnapshot()
}

As soon as we retrieve all of the to-do gadgets, we have to invoke the updateSnapshot methodology to replace the desk view.

Deleting Knowledge from Database

Within the pattern app, we’ve a swipe motion for deleting a row merchandise like this:

let deleteAction = UIContextualAction(fashion: .damaging, title: "Delete") { (motion, sourceView, completionHandler) in

    var snapshot = self.dataSource.snapshot()
    snapshot.deleteItems([todoItem])
    self.dataSource.apply(snapshot, animatingDifferences: true)

    // Name completion handler to dismiss the motion button
    completionHandler(true)
}

For now, it solely removes a to-do merchandise from the desk view however not the database. To utterly delete the merchandise from database, we have to insert a line of code within the closure:

self.container?.mainContext.delete(todoItem)

By calling the delete methodology and offering the related merchandise, SwiftData will care for eradicating the required merchandise from the database, guaranteeing that it’s now not persevered in our app’s knowledge storage.

That is how we migrate the to-do app from utilizing in-memory storage to database utilizing SwiftData.

Abstract

By following the steps outlined above, we efficiently migrated the to-do app from utilizing in-memory storage to using a database with the assistance of SwiftData. As demonstrated, the mixture of the @Mannequin macro and SwiftData framework simplifies the method of incorporating a database into an app.

We hope that via this tutorial, you now possess a clearer understanding of easy methods to combine SwiftData right into a SwiftUI mission and carry out important CRUD (Create, Learn, Replace, Delete) operations. Apple has invested vital effort in making persistent knowledge administration and knowledge modeling extra accessible for Swift builders, together with newcomers to the language.

With SwiftData, you’ve a strong instrument at your disposal to deal with knowledge storage and retrieval effectively. We encourage you to discover additional and leverage the capabilities of SwiftData to boost your app growth journey.