import SwiftUI

struct UserSettings {
    var fontSize: CGFloat = 17
}

struct UserView: View {
    @EnvironmentObject var userSettings: UserSettings
    
    var body: some View {
        VStack {
            Text("Hello, World")
                .font(.system(size: userSettings.fontSize))
            Slider(value: $userSettings.fontSize, in: 10...30)
        }
    }
}

struct ContentView: View {
    var body: some View {
        UserView().environmentObject(UserSettings())
    }
}