SwiftUI Model Updating Example

gistfile1.txt

import SwiftUI

class Model {
    var number: String = "One"
}

struct ContentView: View {
    var body: some View {
        Text("Broken")
        BrokenView()
        Divider()
        Text("Hacky Fix")
        HackyView()
        Divider()
        Text("Wrapper Fix")
        WrapperView()
    }
}

struct BrokenView: View {
    let model = Model()

    var body: some View {
        Text(model.number)
        Button("Change") {
            model.number = ["One", "Two", "Three", "Four", "Five", "Six"].randomElement()!
        }
    }
}

struct HackyView: View {
    let model = Model()

    @State private var updater: Bool = false

    var body: some View {
        Text(model.number)
        Button("Change") {
            model.number = ["One", "Two", "Three", "Four", "Five", "Six"].randomElement()!
            updater.toggle()
        }

        if updater {
            EmptyView()
        }
    }
}

struct WrapperView: View {
    @StateObject var model = PublishedModel(model: Model())

    var body: some View {
        Text(model.number)
        Button("Change") {
            model.number = ["One", "Two", "Three", "Four", "Five", "Six"].randomElement()!
        }
    }

    class PublishedModel: ObservableObject {
        let model: Model

        init(model: Model) {
            self.model = model
            self.number = model.number
        }

        @Published var number: String {
            didSet {
                model.number = number
            }
        }
    }
}