How can I initialize SwiftUI DatePicker .hourAndMinute element? - swift

Question

I am trying to initialize this "WakeUpDate" date element so that the default displayed value is 10:00 AM. This date picker is HourandMinute only and is being stored in userdefaults.
I tried to init the date element but it is not building. With this error: Cannot assign value of type 'State<Date>' to type 'Published<Date>'
UserData: Currently, the following init does not build
import Foundation
import SwiftUI
class UserData: ObservableObject {
init() {
_wakeUpTime = State<Date>(initialValue: Calendar.current.date(DateComponents(Hour: 10)) ?? Date())
}
#Published var wakeUpTime: Date = UserDefaults.standard.object(forKey: "wakeUpTime") as? Date ?? Date() {
didSet {
UserDefaults.standard.set(self.wakeUpTime, forKey: "wakeUpTime")
}
}
}
SettingsDetail: Where the DatePicker is being selected:
struct SettingsDetailView: View {
#ObservedObject var userData: UserData
var body: some View {
Form{
DatePicker("Select a new time", selection: $userData.wakeUpTime, displayedComponents: .hourAndMinute)
}
}
}
MainSettings: Where the selected DatePicker Date is being displayed:
import SwiftUI
import UserNotifications
struct SettingsView: View {
#ObservedObject var userData = UserData()
static var dateFormatter: DateFormatter = {
let formatter = DateFormatter()
formatter.dateFormat = "hh:mm a"
return formatter
}()
var body: some View {
NavigationView {
VStack (alignment: .center, spacing: 0) {
Form{
Section(header: Text("NOTIFICATION SETTINGS")) {
HStack {
Text("Current Notification Time")
.foregroundColor(Color("MainText"))
Spacer()
Text("\(self.userData.wakeUpTime, formatter: SettingsView.self.dateFormatter)")
}
}
}
}
}
}
}
EDIT I tried initializing UserData like this, but now when I pick a new time with the date picker and quit the app, the new time is gone and 5PM (the init time) is displayed again.
import Foundation
import SwiftUI
class UserData: ObservableObject {
init() {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "HH:mm"
if let date = dateFormatter.date(from:"17:00") {
wakeUpTime = date
}
}
#Published var wakeUpTime: Date = UserDefaults.standard.object(forKey: "wakeUpTime") as? Date ?? Date() {
didSet {
UserDefaults.standard.set(self.wakeUpTime, forKey: "wakeUpTime")
}
}
}
How can I run init only on the first launch, and be removed once the selected time has been picked with the datepicker?

Answer 1

I figured it out by doing this:
class UserData: ObservableObject {
#AppStorage("userdatahaslaunched") var userdatahaslaunched = false
init() {
if !userdatahaslaunched {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "HH:mm"
if let date = dateFormatter.date(from:"10:00") {
wakeUpTime = date
}
userdatahaslaunched = true
}
}

Answer 2

If your intent is to let the user initialize a wake up time you should always expect a date after now. So what you are looking for is calendar method nextDate(after:) and you can match the desired components (hour and minute). Note that you don't need to include the minutes component when calling this method if it is zero.
let date = Calendar.current.nextDate(after: Date(), matching: .init(hour: 10), matchingPolicy: .strict)!
print(date.description(with: .current))