Can you explain what the ObservableObject protocol means in programming?

The ObservableObject protocol in programming, especially in SwiftUI, is used to create objects that can notify subscribers about changes to their properties. When an object conforming to ObservableObject changes properties marked with @Published, all subscribers automatically receive a notification and can update the interface.

This allows for a reactive approach to updating the UI without manually managing change events.

Example:

import SwiftUI
import Combine

class UserSettings: ObservableObject {
    @Published var username: String = "Guest"
}

struct ContentView: View {
    @ObservedObject var settings = UserSettings()

    var body: some View {
        Text("Hello, \(settings.username)!")
    }
}