how do i make a swiftui view that displays localUser.name.first automatically update when first changes? localUser and name are both classes, and first is a string

To make a SwiftUI view that automatically updates when localUser.name.first changes, you need to use the @ObservableObject and @Published property wrappers. Here's a step-by-step guide:

1. Define the ObservableObject: Make localUser conform to ObservableObject and mark the first property with @Published.

2. Use the ObservableObject in your View: Use the @ObservedObject property wrapper in your SwiftUI view to observe changes to localUser.

Here's an example implementation:

import SwiftUI
import Combine

// Define the classes
class Name: ObservableObject {
    @Published var first: String
    
    init(first: String) {
        self.first = first
    }
}

class LocalUser: ObservableObject {
    @Published var name: Name
    
    init(name: Name) {
        self.name = name
    }
}

// Define the SwiftUI view
struct ContentView: View {
    @ObservedObject var localUser: LocalUser
    
    var body: some View {
        Text(localUser.name.first)
            .padding()
    }
}

// Example usage
@main
struct MyApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView(localUser: LocalUser(name: Name(first: "John")))
        }
    }
}

In this example:

• Name and LocalUser are both classes that conform to ObservableObject.
• The first property in Name is marked with @Published to notify SwiftUI of changes.
• The ContentView uses @ObservedObject to observe changes to localUser.

When localUser.name.first changes, SwiftUI will automatically update the view to reflect the new value.

For more details on state management in SwiftUI, you can refer to the SwiftUI essentials session from WWDC 2024.