How to use StateObject properly?

Asked on 08/12/2024

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It seems like you're interested in learning about the proper use of StateObject in SwiftUI. While the provided context from WWDC does not directly address StateObject, I can offer some general guidance on its usage.

StateObject is a property wrapper introduced in SwiftUI to manage the lifecycle of an observable object. It is used to create and own an instance of an observable object, ensuring that it is initialized only once during the view's lifecycle. This is particularly useful when you want the view to manage the state of an object that conforms to the ObservableObject protocol.

Here's a basic example of how to use StateObject:

import SwiftUI

class MyViewModel: ObservableObject {
    @Published var count = 0
}

struct ContentView: View {
    @StateObject private var viewModel = MyViewModel()

    var body: some View {
        VStack {
            Text("Count: \(viewModel.count)")
            Button("Increment") {
                viewModel.count += 1
            }
        }
    }
}

In this example, MyViewModel is an observable object with a count property. The ContentView uses @StateObject to create and manage an instance of MyViewModel. The view updates automatically when the count property changes.

If you have specific questions about SwiftUI or related topics from WWDC, feel free to ask!