Why does SwiftUI update function doesn't work? - swiftui

Question

There are 2 views (structs).
First view has a #state update:
struct SettingsView: View {
#State private var lang = 0
#State private var languages = ["English", "Spanish"]
#State private var text1 = "Close"
#State private var text2 = "Settings"
#State var show = false
#State var update = false
var body: some View {
ZStack{
Button(action: {
self.show.toggle()
}) {
Text("Choose language")
}
if self.$show.wrappedValue {
GeometryReader {proxy in
ChooseLanguage(show: self.$show, update: self.$update)
}.background(Color.black.opacity(0.65)
.edgesIgnoringSafeArea(.all)
.onTapGesture {
withAnimation{
self.show.toggle()
}
})
}
}.onAppear{
switch UserDefaults.standard.string(forKey: "languageSettings"){
case "en": self.lang = 0
case "es": self.lang = 1
default: return
}
self.updateLanguage()
}
func updateLanguage(){
if self.lang == 1 {
self.text1 = "Cerrar"
self.text2 = "Configuración"
self.languages = ["Inglés", "Español"]
} else {
self.text1 = "Close"
self.text2 = "Settings"
self.languages = ["English", "Spanish"]
}
}
}
}
The second view has #Binding update:
import SwiftUI
struct ChooseLanguage : View {
var languages = UserDefaults.standard.stringArray(forKey: "langlist")
#Binding var show: Bool
#Binding var update: Bool
var body: some View {
ZStack {
VStack {
Button(action: {
UserDefaults.standard.set("en", forKey: "languageSettings")
UserDefaults.standard.set(["English", "Spanish"], forKey: "langlist")
self.show.toggle()
self.update = true
}) {
Text(languages![0])
}
Button(action: {
UserDefaults.standard.set("es", forKey: "languageSettings")
UserDefaults.standard.set(["Inglés", "Español"], forKey: "langlist")
self.show.toggle()
self.update = true
}) {
Text(languages![1])
}
}
}
}
}
When I call the func updateLanguage() before the .onAppear only errors appear.
Why I can update the values with function from the onAppear and I can't do this from the wrappedValue?
if self.$update.wrappedValue {
self.updateLanguage()
self.update.toggle()
}
This part doesn't work if to place before }.onAppear

Answer 1

As far as I see, you can make it so much easier with using init() method for your view.
There you can declare and initialize all your #State variables with the correct value (depending on your UserDefaults)
Just to show you an example:
struct SetView: View {
#State private var lang : Int
#State private var languages : [String]
#State private var text1 : String
#State private var text2 : String
#State var show = false
#State var update = false
init()
{
var state : Int = 0
switch UserDefaults.standard.string(forKey: "languageSettings")
{
case "en": state = 0
case "es": state = 1
default:
//Default value here
state = 0
}
if state == 1 {
self._lang = State(initialValue: state)
self._text1 = State(initialValue: "Cerrar")
self._text2 = State(initialValue: "Configuración")
self._languages = State(initialValue: ["Inglés", "Español"])
} else {
self._lang = State(initialValue: state)
self._text1 = State(initialValue: "Close")
self._text2 = State(initialValue: "Settings")
self._languages = State(initialValue: ["English", "Spanish"])
}
}
You won't need onAppear method at all, when you initialize your State variables with the correct value from the beginning.
I haven't tested it yet. Code is just out of my mind above.

Answer 2

Instead of calling the function after the #State upload value has been changed easier to send bindings for each text to the popup view.
GeometryReader {proxy in
ChooseLanguage(show: self.$show,
text1: self.$text1,
text2: self.$text2,
languages: self.$languages)
}