swiftUI 中的全局变量？

Question

I want to keep some Boolean state which is going to use in all over the app. is there any way to make such global variable in swiftUI?

Thank You for help

Answer 1

Use the @EnvironmentObject property wrapper for data shared with many views. This lets us share model data anywhere it's needed, while also ensuring that the views automatically stay updated when that data changes.

EnvironmentObject

A property wrapper type for an observable object supplied by a parent or ancestor view. https://developer.apple.com/documentation/swiftui/environmentobject

// Our observable object class
class GameSettings: ObservableObject {
    @Published var score = 0
}

// A view that expects to find a GameSettings object
// in the environment, and shows its score.
struct ScoreView: View {
    @EnvironmentObject var settings: GameSettings

    var body: some View {
        Text("Score: \(settings.score)")
    }
}

// A view that creates the GameSettings object,
// and places it into the environment for the
// navigation view.
struct ContentView: View {
    @StateObject var settings = GameSettings()

    var body: some View {
        NavigationView {
            VStack {
                // A button that writes to the environment settings
                Button("Increase Score") {
                    settings.score += 1
                }

                NavigationLink(destination: ScoreView()) {
                    Text("Show Detail View")
                }
            }
            .frame(height: 200)
        }
        .environmentObject(settings)
    }
}

Ref: https://www.hackingwithswift.com/quick-start/swiftui/how-to-use-environmentobject-to-share-data-between-views

More info

https://developer.apple.com/documentation/swiftui/managing-model-data-in-your-app