View parameter only passed to view when application first loads - SwiftUI - swift

Question

I have a navigation view (SettingsView) as shown below. When I go to PayScheduleForm the first time, the date from UserDefaults is passed properly. If I change the payDate value in PayScheduleForm, I can see that it updates the UserDefaults key properly. However, if I go back to SettingsView, and then go to PayScheduleForm again, the original value is still shown in the picker.
It's kind of an odd scenario so maybe it's better explained step by step:
Start App
Go to Settings -> Pay Schedule
Last UserDefaults payDate value is in DatePicker (10/08/2020)
Change value to 10/14/2020 - console shows that string of UserDefaults.standard.object(forKey: "payDate") = 10/14/2020
Go back to settings (using back button)
Go back to Pay Schedule and see that DatePicker has its original value (10/08/2020)
Of course if I restart the app again, I see 10/14/2020 in the DatePicker
struct SettingsView: View {
var body: some View {
NavigationView{
if #available(iOS 14.0, *) {
List{
NavigationLink(destination: AccountsList()) {
Text("Accounts")
}
NavigationLink(destination: CategoriesList()) {
Text("Categories")
}
NavigationLink(destination: PayScheduleForm(date: getPayDate()).onAppear(){
getPayDate()
}) {
Text("Pay Schedule")
}
}.navigationTitle("Settings")
} else {
// Fallback on earlier versions
}
}.onAppear(perform: {
getUserDefaults()
})
}
func getPayDate() -> Date{
var date = Date()
if UserDefaults.standard.object(forKey: "payDate") != nil {
date = UserDefaults.standard.object(forKey: "payDate") as! Date
}
let df = DateFormatter()
df.dateFormat = "MM/dd/yyyy"
print(df.string(from: date))
return date
}
struct PayScheduleForm: View {
var frequencies = ["Bi-Weekly"]
#Environment(\.managedObjectContext) var context
#State var payFrequency: String?
#State var date: Date
var nextPayDay: String{
let nextPaydate = (Calendar.current.date(byAdding: .day, value: 14, to: date ))
return Utils.dateFormatterMed.string(from: nextPaydate ?? Date() )
}
var body: some View {
Form{
Picker(selection: $payFrequency, label: Text("Pay Frequency")) {
if #available(iOS 14.0, *) {
ForEach(0 ..< frequencies.count) {
Text(self.frequencies[$0]).tag(payFrequency)
}.onChange(of: payFrequency, perform: { value in
UserDefaults.standard.set(payFrequency, forKey:"payFrequency")
print(UserDefaults.standard.string(forKey:"payFrequency")!)
})
} else {
// Fallback on earlier versions
}
}
if #available(iOS 14.0, *) {
DatePicker(selection: $date, displayedComponents: .date) {
Text("Last Payday")
}
.onChange(of: date, perform: { value in
UserDefaults.standard.set(date, forKey: "payDate")
let date = UserDefaults.standard.object(forKey: "payDate") as! Date
let df = DateFormatter()
df.dateFormat = "MM/dd/yyyy"
print(df.string(from: date))
})
} else {
// Fallback on earlier versions
}
}
```

Answer 1

Fixed this. Posting so others with the same issue can find the answer.
iOS 14 allows the #AppStorage property wrapper which easily allows access to UserDefaults, BUT the Date type is not allowed with #AppStorage as of now.
Instead you can use an #Observable object
First create a swift file called UserSettings.swift and create a class in there:
class UserSettings: ObservableObject {
#Published var date: Date {
didSet {
UserDefaults.standard.set(date, forKey: "payDate")
}
}
init() {
self.date = UserDefaults.standard.object(forKey: "payDate") as? Date ?? Date()
}
}
Then add an #ObservableObject to your view
#ObservedObject var userSettings = UserSettings()
...
DatePicker(selection: $userSettings.date, displayedComponents: .date) {
Text("Last Payday")
}