AView.swift
import SwiftUI
struct AView: View {
var body: some View {
Button(action: {
UserDefaults.standard.setValue(true, forKey: "userIsLogged")
}, label: {
Text("Change User Defaults")
})
}
}
BView.swift
import SwiftUI
struct BView: View {
@State var userIsLogged: Bool = UserDefaults.standard.bool(forKey: "userIsLogged")
var body: some View {
Text(String(userIsLogged))
.background(Color.blue)
.onAppear{
// update this value
userIsLogged = UserDefaults.standard.bool(forKey: "userIsLogged")
}
}
}
ContentView.swift
import SwiftUI
struct ContentView: View {
var body: some View {
NavigationView {
VStack{
AView()
NavigationLink(
destination: BView(),
label: {
Text("Navigate to BView")
})
}
}
}
}
This example shows one view (AView.swift) changed the UserDefaults, the situation of updating of another view (BView.swift) of UserDefaults.
- the variable
userIsLoggedin BView get the value of UserDefaults at same time as AView, so withoutonAppear, you will the BView is not changed, since the variable once get assigned, will not change, same asinit. - But
onAppearwill get called whenever the view is about to present, here we check the newest UserDefaults value and assign that to userIsLogged.