How Share Variables Among View and Sub Views in SwiftUI - swiftui

Question

I have a date picker, when the date selection value changes, I would like to store it in a string array called filterSelections, how do I do that? Thanks in advance.
import SwiftUI
public var filterSelections: [String: Any]?
func setFilterSelections(name: String, selectedValue: Any) {
filterSelections[name] = selectedValue
}
struct myMainSwiftUIView: View{
var body: some View {
ScrollView {
VStack{
mySub1View()
}
}
}
}
struct mySub1View: View {
#State public var fromDate: Date = Calendar.current.date(byAdding: DateComponents(year: -40), to: Date()) ?? Date()
var body: some View {
HStack(spacing:10) {
VStack(alignment:.leading, spacing:20) {
DatePicker(selection: $fromDate, displayedComponents: .date) {
Text("From")
.font(.body)
.fixedSize()
}
}
}
}
}
}

Answer 1

It's hard for me to see the application of what storing all of the changes to the date picker would be, since there wouldn't be any way to cancel them out (and, in pre-iOS 14, I think the wheel would make this a particular crazy looking list when things were changing).
My suspicion is that you probably want the date along with some other filters added together. And, you specified wanting to share that state between views and subviews, which I've tried to accommodate. I also used the date format that you asked for.
I did not include the [String:Any] as your question said "array", not dictionary.
Lots of guess work here, since it's not totally clear what your goal is, but hopefully this gives you some ideas of how to share state.
class FilterViewModel : ObservableObject {
#Published var dateFilter : Date = Calendar.current.date(byAdding: DateComponents(year: -40), to: Date()) ?? Date()
#Published var myOtherFilter = "Filter1"
static var formatter = DateFormatter()
var allFilters : [String] {
Self.formatter.dateFormat = "yyyy/MM/dd"
return [myOtherFilter, Self.formatter.string(from: dateFilter)]
}
}
struct ContentView: View{
#StateObject private var filterModel = FilterViewModel()
var body: some View {
ScrollView {
VStack{
MySub1View(filterModel: filterModel)
}
ForEach(filterModel.allFilters, id: \.self) { filter in
Text(filter)
}
}
}
}
struct MySub1View: View {
#ObservedObject var filterModel : FilterViewModel
var body: some View {
HStack(spacing:10) {
VStack(alignment:.leading, spacing:20) {
DatePicker(selection: $filterModel.dateFilter, displayedComponents: .date) {
Text("From")
.font(.body)
.fixedSize()
}
}
}
}
}

Answer 2

It is so simple, make an array and store all of them, do not make more complex in your code, if you want export your Date array then use StateObject, there is really not a big issue. after all then start working on your stored array, for example where and how you want use it!
import SwiftUI
struct ContentView: View {
var body: some View {
mySub1View()
}
}
struct mySub1View: View {
#State private var selection: Date = Date()
#State private var selectionArray: [Date] = [Date]()
var body: some View {
if #available(iOS 14.0, *) {
DatePicker(selection.description, selection: $selection, displayedComponents: .date)
.onChange(of: selection) { newValue in
selectionArray.append(newValue)
print(selectionArray)
}
}
}
}