ObservableObject doesn't update view with TImer

Question

I'm trying to understand why StateObject doesn't update my Text view while it's being updated by timer inside ObservableObject. I would really appreciate any explanation.

struct DailyNotificaitonView: View {
    @StateObject var x = Test2()
    
    var body: some View {
        VStack {
            Text("\(x.progress.x)")
                .onAppear {
                    Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { _ in
                        DispatchQueue.main.async {
                            print(x.progress.x)
                        }
                    } 
              }
        }
    }

ObservableObject:

class Test2: ObservableObject {
    @ObservedObject var progress = Test()
    
    init() {
        Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { _ in
            DispatchQueue.main.async {
                self.update()
            }
        }
        
        
    }
    
    func update() {
        print("updated")
        progress.x += 1
        progress.y += 1
    }
}

class Test: ObservableObject {
    @Published var x: Int = 0 {
        willSet {
            objectWillChange.send()
        }
    }
    @Published var y: Int = 0
}

I highly recommend to use a Timer Publisher from the Combine framework — vadian, Jul 31 '22 at 07:32
@Published needs to be a value type, e.g. a struct or an array or structs. — malhal, Jul 31 '22 at 11:00
ObservedObject Wrapper can’t be inside a class it has to be in a View. Also the object will change line is redundant. — lorem ipsum, Jul 31 '22 at 11:14

score 0 · Answer 1 · edited Jul 31 '22 at 10:55

0

At a high level, the issue you are having is that progress is not an @Published value, e.g. struct or array, which is necessary for an ObservedObject to receive the state changes. At its core, the published/observed system in SwiftUI is designed to have an observed object directly reference a published value.

edited Jul 31 '22 at 10:55

malhal

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answered Jul 31 '22 at 06:49

Allison Poppe

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ObservableObject doesn't update view with TImer

1 Answers1