SwiftUI - how to save settings selections - swiftui

Question

import SwiftUI
struct CardTheme: View {
//#State private var theme = 0
#State private var theme = UserDefaults.standard.integer(forKey: "Card Theme")
var body: some View {
List {
HStack {
Text("Mono")
//.font(.system(size: 12))
.onTapGesture {
self.setTheme(i: 0)
}
Spacer()
if(theme == 0) {
Image(systemName: "checkmark")
.foregroundColor(Color.green)
}
}
HStack {
Text("Cool")
// .font(.system(size: 12))
.onTapGesture {
self.setTheme(i: 1)
}
Spacer()
if(theme == 1) {
Image(systemName: "checkmark")
.foregroundColor(Color.green)
}
}
HStack {
Text("Cute")
// .font(.system(size: 12))
.onTapGesture {
self.setTheme(i: 2)
}
Spacer()
if(theme == 2) {
Image(systemName: "checkmark")
.foregroundColor(Color.green)
}
}
}
.navigationBarTitle(Text(verbatim: "Card Theme"))
}
func setTheme(i: Int) {
theme = i
UserDefaults.standard.set(i, forKey: "Card Theme")
}
}
I have a settings menu where the user picks a theme, the default value is set to a global variable, globalVarTheme, which is 0. But after they make a selection, exit that menu, and re-enter the menu it goes back to 0 (the first item) even if they have chosen one of the other items. How do I save their selection?
Also, what is the best way to save user selections beyond the current app session? Should I write all their selections to a plist file or is there a conventional way?

Answer 1

#State is used for the changes within a given view. It is not meant to persist across the views. Instead use #Environment property wrapper. WWDC 2019 talks about that when to use what.

Answer 2

#State isn't the right PropertyWrapper.
If you want to use your settings in multiple views than use #EnvironmentObject as the PropertyWrapper.
You can read about the different PropertyWrappers here:
https://medium.com/#alex.hsieh/state-objectbinding-and-environmentobject-in-swiftui-783588b60671
If you want to save the Settings beyond the current app session you can use UserDefauls.
How do I use UserDefaults with SwiftUI?