Premise

I have a MultiDatePicker bounded to a closed range of the current month. In addition, I have a datePicker representing a "Start Date" that is the current day. I want the Day of the Month from "Start Date" to be pre-selected in the MultiDatePicker.

Example Code

import SwiftUI
import SwiftData

struct ContentView: View {
    @Environment(\.modelContext) private var modelContext
    
    @State private var days: Set = []

    var body: some View {
        VStack {
            
            Text("Selected Days")
            
            let dayArray = Array(days)
            ForEach(dayArray, id: \.self) { day in
                Text(Calendar.current.date(from: day)?.formatted(date: .complete, time: .complete) ?? "")
                
            }
            
            MultiDatePicker("", selection: $days)
        }
    }
}
    
#Preview {
    ContentView()
        .modelContainer(for: Item.self, inMemory: true)
}

Attempted Solution

I have attempted to add a DateComponent in the initial value for days, like this

@State private var days: Set = [DateComponents(year: 2025, month: 11, day: 19)]

(In my fully-implemented version, I use values from "Start Date" and the current Date. From testing, hard-coding the date did not seem to affect my outcome. They are hard-coded here for simplicity)

Problem: For some reason, I am unable to remove this default option from the picker. When de-selecting the current date from the picker,

1. The date never leaves the list of selected dates
2. The date re-appears when closing the picker and re-opening it
3. The de-selection doesn't call a .onChange(of: days) {...}

Observation: In my fully implemented version of this, I've found I'm able to double-select the pre-selected date. I do this by first de-selecting (which doesn't remove it), then re-selecting it (which adds the second instance).

This gave me the suspicion that, at times, I'm storing 2 instances of DateComponents with the same date values, but different time values.

After printing all DateComponents stored, I observed that the two instances of DateComponent sharing that Day of the Month are identical in date and time down to the second.