ObservableObject

A type of object with a publisher that emits before the object has changed.

By default an ObservableObject will synthesize an objectWillChangepublisher that emits before any of its @Published properties changes

class DelayedUpdater: ObservableObject {
    
    @Published var value = 0
    // or, use below to add extra functionality.
    var value: Int {
        willSet {
            objectWillChange.send()
        }
    }
    
    init() {
        for i in 1...10 {
            DispatchQueue.main.asyncAfter(deadline: .now() + Double(i)) {
                self.value += 1
            }
        }
    }

}

struct ContentView: View {

    @ObservedObject var updater = DelayedUpdater()
    
    var body: some View {
        Text("value: \(updater.value)")
        // value: 0
        // value: 1
        // value: 2
        // ..
    } 
}