Linking ObservableObject to DatePicker in SwiftUI - swift

Question

I am new to Swift and all its frameworks. I have a JSON file with readings for each day of the year. I have made a Decodable struct for the reading and an ObservableObject class which stores the readings in an array. I have made the ObservableObject an #EnvironmentObject so it can be accessed in all views. Can I link the readings to the date picker so that selecting a date will take me to a detailed view?
import SwiftUI
struct CalendarView: View {
// this is where ObserveableObject is required
#EnvironmentObject var days: Days
#State private var date = Date()
let dateFormatter: DateFormatter = {
let formatter = DateFormatter()
// formatter.dateStyle = .long
formatter.dateFormat = "LLLL d"
return formatter
}()
var body: some View {
VStack {
Text("Select a date to read")
.font(.largeTitle)
DatePicker("Select a date", selection: $date, displayedComponents: .date)
.datePickerStyle(GraphicalDatePickerStyle())
.labelsHidden()
.frame(maxHeight: 400)
Text("\(date, formatter: dateFormatter)")
}
.navigationTitle("Datepicker")
}
}
struct CalendarView_Previews: PreviewProvider {
static var previews: some View {
CalendarView()
}
}

Answer 1

//Replace this with your Decodable object
class Day : ObservableObject{
let id: UUID = UUID()
var date: Date
init( date: Date) {
self.date = date
}
}
class CalendarViewModel: ObservableObject, Identifiable {
#Published var days: [Day] = []
#Published var selectedDate: Date = Date()
var filteredDay: Day?{
days.filter({
Calendar.current.isDate($0.date, equalTo: selectedDate, toGranularity: .day)
}).first
}
init() {
//Create sample Days you can remove this and populate your array with acual data
for n in 1...30{
days.append(Day(date: Date().addingTimeInterval(TimeInterval(60*60*24*n))))
days.append(Day(date: Date().addingTimeInterval(TimeInterval(-60*60*24*n))))
}
}
}
struct CalendarView: View {
#StateObject var vm: CalendarViewModel = CalendarViewModel()
#State var isVisible: Bool = false
let dateFormatter: DateFormatter = {
let formatter = DateFormatter()
// formatter.dateStyle = .long
formatter.dateFormat = "LLLL d"
return formatter
}()
var body: some View {
NavigationView{
ScrollView {
Text("Select a date to read")
.font(.largeTitle)
DatePicker("Select a date", selection: $vm.selectedDate, displayedComponents: .date)
.datePickerStyle(GraphicalDatePickerStyle())
.labelsHidden()
.frame(maxHeight: 400)
Text("\(vm.selectedDate, formatter: dateFormatter)")
if vm.filteredDay != nil{
NavigationLink(
destination: DayView(day: vm.filteredDay!),
isActive: $isVisible,
label: {
Text("View Day")
})
}else{
Text("No results for selected day")
}
}
.navigationTitle("Datepicker")
}
}
}
struct DayView:View {
//Observe the actual Day here for changes
#ObservedObject var day: Day
let dateFormatter: DateFormatter = {
let formatter = DateFormatter()
// formatter.dateStyle = .long
formatter.dateFormat = "LLLL d"
return formatter
}()
var body: some View {
VStack{
Text(dateFormatter.string(from: day.date))
}
}
}