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swiftuiproperty-wrapperappstorage

SwiftUI - How to access and update an @AppStorage var from multiple Views?

Is there a better way to use @AppStorage variables than through a Binding as shown below?

Is there a way to access UserDefaults in the environment?

struct ContentView: View {
    @AppStorage("darkMode") var darkMode = false

    var body: some View {
            SubView(darkMode: $darkMode)
        }
    }
}

struct SubView: View {
    @Binding var darkMode: Bool
    var body: some View {
        Text("Dark Mode is \(darkMode == true ? "on" : "off")")
    }
}
Solution

  • By using @AppStorage in different views you still access the same UserDefaults.standard storage (unless you explicitly specify the suiteName).

    Which means you can just use the @AppStorage directly in the subview.

    struct ContentView: View {
    @AppStorage("darkMode") var darkMode = DefaultSettings.darkMode

    var body: some View {
        VStack {
            Button("Toggle dark mode") {
                self.darkMode.toggle()
            }
            SubView()
        }
        .colorScheme(darkMode ? .dark : .light)
        .preferredColorScheme(darkMode ? .dark : .light)
    }
}

struct SubView: View {
    @AppStorage("darkMode") var darkMode = DefaultSettings.darkMode

    var body: some View {
        Text("Dark Mode is \(darkMode == true ? "on" : "off")")
    }
}

enum DefaultSettings {
    static let darkMode = false
}

    Note: the default darkMode value is extracted (to the DefaultSettings enum) so you don't repeat false in each view.

    Alternatively you can inject @AppStorage directly to the environment. See: